Pretending To Be A 'Good Nurse,' Serial Killer Targeted Patients

Transcript

TERRY GROSS, HOST:

This is FRESH AIR. I'm Terry Gross. In 2003, police in Somerset County, New Jersey arrested a hospital nurse named Charlie Cullen who was suspected of injecting patients with lethal doses of a variety of medications. Cullen would turn out to be one of the nation's most prolific serial killers, murdering dozens, perhaps hundreds of people in nine hospitals over a 16-year period.

Our guest, journalist Charles Graeber, spent six years investigating the Cullen case and is the only reporter to speak to Cullen in prison. Graeber's new book, "The Good Nurse," focuses not only on Graeber's tortured life and crimes but on why it took so long to stop him despite plenty of evidence he was harming patients.

In case after case, Graeber writes, hospital staff believed Cullen was harming patients and pressured him to leave, but failed to alert state regulators or take other steps that might have ended his killing spree. Charles Graeber has written for Wired, GQ, New York Magazine and other publications. "The Good Nurse" is his first book. He spoke with FRESH AIR contributor Dave Davies.

DAVE DAVIES, HOST:

Well, Charles Graeber, welcome to FRESH AIR. This is a remarkable story both of a serial killer and what drove him to commit these crimes, but also one about the health care system and its vulnerability to someone who abuses patients. And I want to start with one of his - maybe his earliest employment at the Saint Barnabas Medical Center in Livingston, New Jersey.

And you write that in 1991, he'd been there a few years, and some of the staff noticed some weird stuff. What did they find?

CHARLES GRAEBER: Right. Well, he'd been there since '87. It was his first job out of nursing school. He started there right out of his honeymoon. And on the ICU ward and CCU wards, they started finding that patients were mysteriously crashing. They would hook a patient up to an IV that was supposed to have saline or something of the like, and the patient became a magical diabetic and where they were on this terrible diabetic roller-coaster ride, woozing(ph) in and out of consciousness and burning through sugar, and they couldn't out-feed the fire.

And then eventually they'd get so bad that they'd unhook them from the lines and rush them in for more emergency procedures, and once they unhooked the lines, everything changed. They were fine again.

DAVIES: That's the line connected to an IV bag, right?

GRAEBER: Correct, correct. So once they unhooked them from the IV, they were OK, and trial and error, a few of these on the ward, and they started questioning the IV bags themselves and brought them in and found that in fact they'd been compromised. There were extra pinpricks in them, and when they analyzed the IV bags, they found that instead of containing saline, the IV bags that had been stored in the medical closet also contained insulin.

DAVIES: So it appeared someone had taken a hypodermic needle with insulin and injected them into the IV bags, leaving virtually no trace, and then causing catastrophic consequences for the patients.

GRAEBER: Exactly, and it was the only conclusion anyone could come to. But it was beyond thinking, because why would anyone do that, who would do that. Suspicion immediately fell to somebody with a specific vendetta, some sort of family member or - you know, it was really very abstract. The hospital had never dealt with anything like this before.

And eventually nurses were cross-indexed, shifts were cross-indexed, and a few names came together, and one name finally stood out more than any, at least according to the head of security there, Thomas Arnold(ph). And that name was Charles Cullen.

DAVIES: And he was the nurse at the center of this. Did some of these folks die?

GRAEBER: People died at Saint Barnabas. It's very difficult to say who died of what. Saint Barnabas is so long ago, and at the time they didn't catch him. I mean, they had him. They strongly suspected him. Tom Arnold said he knew Cullen was dirty, but could they prove it? So it was very difficult to sort out Cullen's personal death toll from the cadence of mortality at a hospital.

Later, speaking to Essex County detectives, the county that Saint Barnabas is in, Cullen said that he was dosing people and with the intent of killing them two or three times a week, not knowing where those bombs went out. And to date, they've only been able to identify one person from the five years definitively that died during his Saint Barnabas time.

So obviously there's a huge fog of time, five years times two or three a week, that's totally unaccounted for.

DAVIES: Right but enormous damage, no doubt. So the investigation focuses on him. What happens?

GRAEBER: Well, he's investigated, pressured, interviewed, tells them essentially there's nothing you can do, you can't hold me, you don't have anything on me, you're just picking on me; leaves, is contemptuous, which really riles the detectives, former cops. They go to the chief of police in the town of Livingston, and the chief, for whatever reason, bounces it right back to the hospital and says this is internal, you guys deal with it, you figure out what happens.

And they don't figure out what happens. Cullen ends up as a floater. He's basically working at the hospital fulltime, but he's staffed by an outside but wholly owned staffing agency of the hospital, which makes tying him to the hospital and specific shifts all the more difficult. And they're still investigating when suddenly they stop giving him shifts.

It's not technically being fired; he's just no longer on the list, and he moves on. And their problems move on with him.

DAVIES: And it's interesting. He doesn't exactly deny it in the interviews.

GRAEBER: No, no, he doesn't - he very rarely denies anything, except during polygraphs, which he passes.

DAVIES: Right, we can get to that. He was good at that. What's fascinating is he goes down to the next job, and when they ask about previous employment, he lists Saint Barnabas, the place where they'd discovered him effectively killing people.

GRAEBER: Sure.

DAVIES: And any impact?

GRAEBER: No, I mean, in fact it worked out really well because they fired him in the beginning of January, and he managed to get over to applying to his next hospital, which was Warren Hospital, at the end of January of 1992. And so he was able to say dates of employment, X date to January 1992, which made it look like he was currently employed and simply wanted a change, rather than having been canned.

And he was given neutral references, which was the norm and the pattern over and over again. And during a nursing shortage with neutral references, seemingly, you know, a nurse that was willing to work nights and weekends and holidays and seemed to bring extra energy with every shift and a lot of experience, that was a nurse worth hiring.

DAVIES: Now I have to note that this happened in 1991, 12 years before the investigation that ultimately caught him. This was - clearly he'd been doing enormous damage, possibly killing patients, and he moves on, works at another seven hospitals, right?

GRAEBER: Yeah, well total of nine, yeah.

DAVIES: Right, OK, so another eight, then. And in case after case, I mean, this is not the only time in which his conduct is suspicious, and supervisors noticed, and he gets questioned, and he moves on and again and again gets new jobs, accurately listing his previous employers as references. Did you ever find a single case of an employer who warned somebody, stay away from this guy?

GRAEBER: Well interestingly enough, the employers that did that were the ones that were most in the wrong for it. At Saint Luke's Hospital in Pennsylvania, some years later, tending towards 2000 almost, he was fired after being caught trashing medicine, basically had been taking good meds and throwing them in the sharps bin of the medical closet.

And upon examination, many of those meds were dangerous meds, and many of them were, in fact, empty, and there'd been no prescriptions for those medications in question.

DAVIES: So it appeared he might have been stealing them for future use?

GRAEBER: Stealing them, stockpiling them for future use, or the suspicion at the time was using them on patients on the ward. And in fact he was doing the latter, and he was caught. Outside counsel was brought in that night, he was grilled. He was moved on. He was offered neutral references and took them and removed from the building, but the hospital administrators called their peers in the immediate circle asking for more information about Charles Cullen and also informing them that Charles Cullen was not considered for rehire at their hospital and shouldn't be at theirs, either.

A judge found later, when this secret behavior came to light, that - well, his issue was that it was the ultimate tyranny, deciding that these administrators had decided who would live and who would die by which hospitals they called and which they did not. A hospital they did not call, for example, was Somerset Medical Center, where Charles Cullen moved on and killed at least another 16 patients that we know of.

DAVIES: Now was there any requirement that hospitals report this stuff to the state health department or an agency that regulates nursing?

GRAEBER: Yeah, you really have to look at that case by case, and that's one of the reasons I took on this book and the reason it took as many years as it did. Some incidents, sentinel events, events that result in actions that are of potential harm to patients, are supposed to be reported to the state nursing board. Other incidents, such as medication errors that are more routine, he had a lot of those, as well, and it's again difficult to sort out which were legitimate mistakes and which were simply the MO of murder. And more of those should have been reported.

Very few were, and the question time after time is: Should more have been reported? Yes, absolutely. And you have to go hospital by hospital, case by case, and really look at which incidents should have been reported. It's also - one needs to be careful, at least I certainly need to be careful. I wanted the reader to be able to put the facts together.

The facts had been buried for a long time. No one was speaking. Charles Cullen speaks only to me. He'd never spoken to any other media. He is not happy that this is coming out. The hospitals have not spoken at all except to give a very basic story about, you know, having been duped and then the last one having caught him.

And the detectives were largely unavailable for comment, as well. So this story, laying it out so that a reader can see the facts laid side by side and decide for themselves the culpability of the hospitals, what they knew, when they knew, what they should have done. And certainly laws have changed in the wake of this.

DAVIES: Right, I want to move on to talk about Charlie Cullen in a moment here, but, I mean, an obvious motive for a hospital to be careful about telling anybody else that they had somebody in their system who harmed or killed patients is fear of lawsuits, right?

GRAEBER: Absolutely, and that's a legitimate fear. Hospitals get sued all the time. They have to carry huge insurance burdens, as do doctors. Their first instinct is to cover themselves, and I don't mean to confuse that with a cover-up, I don't know that that was always the case. It is beyond the imagination of most people, most hospital administrators, to ever think that their staff are killing their patients. They're really there to do the opposite.

So it does take a leap of imagination. I do know that the first actions you see time and time again in these hospitals is a legal action rather than an effective investigative reaction. And oftentimes you'll find that comes in - certainly in retrospect to be a real burden of evidence against one guy, Charles Cullen, even before they can say for sure what he's doing, when it starts to really look like this guy is dirty, that's the time he gets moved on. One way or the other, he's pushed out or pressured out.

So did the hospitals know? That's a question a reader needs to ask, and I think I've provided enough evidence that they'll be able to draw that conclusion. But certainly he should have been stopped before he was, and because he wasn't, he killed a lot more people.

DAVIES: We're speaking with investigative journalist Charles Graeber. His new book about serial killer Charlie Cullen is called "The Good Nurse." We'll talk more after a short break. This is FRESH AIR.

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DAVIES: This is FRESH AIR, and our guest is investigative journalist Charles Graeber. He has a book about Charles Cullen, who was a nurse who killed an untold number of people over many years at hospitals in Pennsylvania and New Jersey. Graeber's new book about the case is called "The Good Nurse."

Let's talk about Charlie Cullen. Very troubled childhood, right?

GRAEBER: Yeah, he describes it as miserable. This is a really dark period not only for Charlie but also for anyone investigating Charlie Cullen. It's a land of shadows, a world he doesn't talk very much about. It's a world that if you were to ask him straight about his childhood, you would not get very much. You tend to learn more about his childhood talking about other topics and then hearing echoes of his childhood, references.

He grew up the youngest of eight, the youngest by a long shot, sort of an unexpected child. His father died only months after his birth. His mother survived largely on sewing and charity. There was a sickly aunt that had moved in with them. He had two brothers with chemical abuse problems and a host of sisters that came in and out of the house, and he - he felt extremely close to his mother. His mother was the figure that protected him.

But the darkness in that house and exactly what happened in that house set the tone for the rest of his life.

DAVIES: Darkness meaning like drug addicts coming in, doing who knows what in rooms, abusing him in some cases?

GRAEBER: It's really hard to say. When asked directly about abuse of that sort in the house, he gets very angry. He's gotten very angry with family members, with ex-wives when they've tried to get him to seek counseling, when they've tried to take him aside, because the pattern - it certainly seems to fit the pattern. He won't say.

But he felt unsafe. There were strange men in and out of that house. He had a brother-in-law that came to live with one of his sisters when his sister was pregnant. There was a lot of domestic violence surrounding that. Exactly what happened to the child is not clear. But eventually the sister ran away, but the brother-in-law stayed, and he and Charlie had a tortured relationship that Charlie had reported to at least one, if not two, of his later lovers that he had tried to poison that brother's drink with - he put lighter fluid in the vodka, which is sort of an early example of what would become his pattern for life, a way of passively dealing with things.

DAVIES: He serves in the Navy. There are a number of examples of bizarre behavior there and apparent suicide attempts. You talked to him a lot of times. Did you feel like you got a sense of what his issues were? Is there a psychiatric diagnosis of Charlie Cullen?

GRAEBER: Yeah, well, he's not crazy in the sense that clinicians use that term. Well, clinicians don't use that term. He's oftentimes very funny, seems to have great self-humor. When I say funny, he's not cracking jokes and being crass. It's quite the opposite. It's self-deprecating, insightful, sardonic and seems quite with it, and you can understand why he was able to succeed, why he was charming, why, you know, he had no romantic - you know, he had no problem finding romantic partners and the like.

Other times his thinking is circular, quite narcissistic, and then the question is how far does that narcissism go? Is it sociopathic? And the answer to that lies somewhere in - well, you have to ask yourself what sort of a person can kill someone and be there as they die and not have it seem to really affect their day at all or in fact affect their future behavior in any negative fashion for 16 years.

You know, he started - he entered nursing in 1987. He said he killed his first patient in 1987. So, you know, this is a lifelong condition. It's almost a compulsion. And what it meant to him I guess is the real question of that, and I don't think it meant that much.

DAVIES: When he was in the hospital and injecting patients with a whole variety of drugs and killing some, you know, this isn't a case of suffering patients who died peaceful deaths, right. I mean, some of these were pretty horrific.

GRAEBER: Yeah, he's often misunderstood - to the extent that anyone knows him at all, he's often called a mercy killer. They called him an angel of death, and that's what that refers to. And the point here is that it was never about the patients. It was never about what the patients needed or even - or wanted, regardless of how appropriate. It was always about what Charlie Cullen wanted and what Charlie Cullen needed.

And if that meant - well, if that meant putting a man with a broken neck and a halo device into insulin shock, that's what happened. If it meant going back and trying time and time again on a patient that he really had his eye on and sending them into atrial fibrillation, over and over again, and, you know, forcing them to be shocked and paddled and coded, time and time again, that's - that was considered fair game.

Whether that was his goal - he would deny that that was his goal, adamantly. But he's also - he's a smart guy and doesn't want to be seen as - well, he doesn't want to be seen as I see him.

DAVIES: One more thing about Charlie and the killings. I mean, hospitals have what are called code teams, that is to try and resuscitate patients who go into cardiac arrest. They call it a code, right?

GRAEBER: Right.

DAVIES: And Charlie was always among the most active members of that. And in a lot of cases, you write, went in to try and resuscitate patients who were in cardiac arrest very likely because of, you know, medications he had secretly administered to them. And it made me wonder, is - was part of the motivation here, that he wanted to be the hero, the very best guy, very best member of the code team, and demonstrate that by creating these incidents and then rushing in to be the hero?

GRAEBER: Yeah, that's absolutely part of it. Sometimes that's what worked for him. He knew what was wrong with the patient when no one else did. He could be the first to go in there. The other residents remember him jumping on the chest of the patient in just sort of the most dramatic fashion and working - they appreciated his enthusiasm and his passion, but it seemed a little over the top. But the truth was he did what others could not do, and he did receive praise for that - elevated status.

And so there was absolutely an element of ego in the murder, and he was anonymous, but this is a way of actually still claiming coup for some of that - for some of the crime he committed under anonymity.

DAVIES: And he knew how to beat a polygraph test?

GRAEBER: Yeah, I don't - he doesn't speak to that. I know that he did beat a polygraph test. He beat two polygraph tests. And in both cases, he was lying. He also was, you know - again the best I can do with this sort of journalism when you can't see everything, you can't see behind every wall, and not everyone says everything you need that - in order to put the story together fully.

But I can just put the facts next to each other, and the facts next to each other are that here's a guy that worked on cardiac wards administering drugs that regulated heart rhythm and stress levels, and everything else, and also very possibly didn't genuinely feel the sorts of wild winging emotions that you and I might feel thinking back on murder.

And put those things together, and you end up with a guy who doesn't register on a polygraph.

GROSS: Charles Graeber will continue his interview with FRESH AIR contributor Dave Davies in the second half of the show. Graeber's new book is called "The Good Nurse." I'm Terry Gross, and this is FRESH AIR.

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GROSS: This is FRESH AIR. I'm Terry Gross. Let's get back to the interview FRESH AIR contributor Dave Davies recorded with Charles Graeber, author of the new book "The Good Nurse." It's the story of Charlie Cullen, a nurse who became one of the nation's most prolific serial killers, murdering dozens - perhaps hundreds - of patients in nine hospitals over a 16-year period by injecting them with lethal doses of medications. In case after case, hospital staff believed Cullen was harming patients, but failed to take the steps that could have stopped him.

DAVIES: So, how did it all finally come apart? What did Charlie do that finally led to the criminal investigation that put him away?

GRAEBER: Nothing that he hadn't done before. It did finally catch up with him. There was a gathering steam of evidence behind him that, you know, you can only have so many investigations, especially in the age - the mounting age of computers and linked databases to not be able to connect the dots. But what happened was he was at Somerset Medical Center. A number of patients were coding mysteriously. Most were digoxin deaths, digoxin being a heart drug like foxglove; it regulates heart rhythm. Others were insulin deaths. They were on the same ward. They were in multiples.

The hospital noticed it. They had a number of meetings. They asked an assistant pharmacist to call the poison control people to see if they could get help figuring out the math of the chemistry, figuring out when a patient would have to be injected with how much dig - dig, which is digoxin, short for digoxin - how much dig a patient would need to be injected with and when in order to start showing these numbers at, you know, X hour. And in the process of asking for help with the math, of course, they saw in the details, the facts of this started to come out, and alarm bells naturally started to ring.

Outside of the hospital, at New Jersey Poison Control, it was Dr. Bruce Ruck who first was alerted, and he alerted his boss, Dr. Steven Marcus. And Marcus very bluntly took it to the administration of Somerset and said, if you're slow rolling this, you're going to look terrible with your pants down. It looks like, you know, it looks like someone's killing patients in your medical center, and if you don't call, I'm going to call. And, by the way, I've got this on tape.

DAVIES: Yeah. This is fascinating, because you - we have these conversations in your book verbatim, because the Poison Control, I guess, routinely tapes calls like this.

GRAEBER: Yeah. They tape their incoming calls, and these were incoming calls.

DAVIES: So a call that the hospital pharmacist thought was a request for information in - I mean, soon leads to this Dr. Bruce Ruck saying, listen, you have a police problem. Do you hear me? And you have to wonder, if it hadn't been for that interaction, if it wouldn't have been a criminal investigation. I guess you can't know.

GRAEBER: You can't know. Certainly, the hospital - hospitals have a tendency to do everything by committee. They move very slowly. Again, it takes a huge leap of imagination - although, it seems fairly clear here, but it does take a huge leap of imagination and a great large amount of acceptance to ever believe that someone, you know, on staff somewhere in your hospital killing other people in your hospital. You know, that's not why you're there.

So having said that, they retained outside counsel. They had been aware of this problem for months at this point. Charles Cullen was killing people for months. He'd been spoken to about related issues, some of the means by which he was getting his drugs. He was questioned about those means by an outside attorney that the hospital had hired. So this was an ongoing issue at the hospital. It got pushed to the forefront, certainly, by an outside entity refusing to allow that internal process to continue to drag on. And it's terrifying to speculate as to what would've happened if - had he - had Dr. Marcus, Dr. Ruck not pushed it.

DAVIES: So the Somerset County Prosecutor's Office launches an investigation, and this is not the kind of thing they're used to doing. They don't have a lot of heavy-duty murders there, anyway, and this is a very specialized kind of crime. Two detectives, Tim Braun, Danny Baldwin get assigned. And, of course, they know that, you know, that most of the information is going to be at the hospital. They approach the hospital. What do they get?

GRAEBER: Right. These guys, Tim and Danny, I spent a lot of time with them. They're really great guys, interesting characters, and were really blunt with me. They came from Newark, which was the murder capital of the world when they were there, Newark Homicide. And as Tim put it, me and Danny, you know, we're street guys. We're blood-and-guts guys. You know, give me a - I've got to delete half the words here but, you know, give me a good old-fashioned street murder, as opposed to this Latin stuff. Because what they were presented with was they weren't even sure if they had a murder. They thought maybe it was just a well-connected guy and some sort of a litigious situation where they couldn't figure out where inappropriate drugs had come from or gone to and...

DAVIES: A well-connected victim trying to make something of it. Right. Right.

GRAEBER: Exactly. A well-connected victim, because it was a - it's a wealthy county, one of the more wealthy counties in America, and as you say, not a lot of murder there. And they proceed because they have to. They've got stacks of medical charts, which apparently the hospital themselves had already gone through. You know, as they would put it, guys with letters after their name had already looked at this stuff for four months, and they didn't find anything. Now they're handing it to us like we're going to, you know, trace this thing like a bullet. They were completely confused.

DAVIES: But here's what's fascinating. So they give - the hospital people, having conducted their own investigation, having spoken to many, many nurses and other staff, give these detectives I think a four-page document, which is not very informative, and then tell the detectives they did not take notes in their interviews of the nurses and other staff, which just seems completely unbelievable, doesn't it?

GRAEBER: It did to them.

DAVIES: Yeah.

GRAEBER: They were really upset. Tim and Danny, the detectives, were very upset. It didn't strike them as being true or helpful.

DAVIES: Right. Now, there was another thing. There was a technical system that the hospital had for dispensing medication, which keeps a record when a nurse has to log in to either - to request and withdraw medication, or to cancel a previous request. And so there is data on which nurses have requested which medications, date and time, right?

GRAEBER: Right.

DAVIES: And when the detectives ask for that data about these nurses in the patients in question, they are told what?

GRAEBER: Right. It's called a Pyxis machine, and they asked for the records. It would be like asking for all the receipts for the last, you know, period of time that, you know, you say these victims died over this period of time. Can we see everything that happened to them? And they are told flatly that all those records are erased from the system two months after, within two months, which would mean that every single victim that they're looking at has no medication records.

DAVIES: And then when they check with the company that makes the system, they discover what?

GRAEBER: Yes. Quite a few steps later, when they're beating their heads against the wall, saying how do we solve a maybe murder with no evidence whatsoever, not even a paper trail - in fact, they're questioning whether they're even murders and contemplating early retirement - they do call the company that owns the thing. And the immediate response is no, of course. It's all the - the data is stored forever. Why would it dump data every two months? That doesn't make any sense. Are you having a problem with your machine? And that creates a whole new dynamic. That really is what cracks the case. It also really pisses off the detectives.

DAVIES: Right. And I have to say, I mean, when I read the book, I am as horrified by what hospital administrators do and don't do as I am by what Charlie Cullen does in a lot of cases here. And you have a case here where Charlie Cullen had clearly been doing some very, very scary stuff, and the hospital had investigated it. And not only did they not volunteer the information to law enforcement, not only did they not share it with law enforcement, they told them things that were untrue, which, by any common understanding of the term, impeded the investigation. Am I missing something here?

GRAEBER: No.

(LAUGHTER)

DAVIES: Right. All right. I have to just get that out and make it clear. And I also want to note that you did - as you write in the book - contact each of the hospitals where Charlie Cullen had worked and done stuff. And Somerset Medical Center gave you a statement, which I think we should read here in full. It said: (Reading) Somerset Medical Center fully cooperated with all interested parties and agencies throughout the course of the Cullen investigation. At this time, we are devoting the full extent of our resources and efforts on delivering the highest quality of care to the members of our community.

That's the beginning and end of what you got from them?

GRAEBER: I received one more communication. The risk manager, who had been the point person for those communications about the medical records and the like, that was obviously someone that I was very interested in speaking with. And that person was, I was informed, not going to be available to be spoken with. But no change in the bottom line.

DAVIES: All right. And we should say that there were never any actions, any official or criminal actions taken against hospital administrations for any of these events, right?

GRAEBER: That's correct.

DAVIES: OK.

GRAEBER: As far as I know, that is correct.

DAVIES: So what does Charlie Cullen stand convicted of? And do we know how many people he may have actually killed?

GRAEBER: We'll never know how many people Charlie Cullen ultimately killed. Charlie Cullen doesn't know how many people he killed. He initially could recall 40, and also said there was a large part of his life that was a fog, during which he would have no ability to recall. But during that fog - those fogs lasted years, and he said that there were probably multiples a week to other detectives.

He was convicted of at least 29, and then civil court, another, I believe, eight. The specifics are confusing, because the further back you go, the fewer records there are. There are no medical records, really, that come out of St. Barnabas. There are very few records of that initial investigation. There are no bodies that one could look at. There was no Pyxis. And so during that five years, you've got one murder, even though he - Cullen himself has said there are far more...

DAVIES: That's the first hospital where he worked in the burn unit and was so active. Right. Right.

GRAEBER: Exactly. So, but fast forward 16 years and look at the last six months, right before he's caught, where there are bodies in the ground that can be autopsied, there are medical records they discover, both the patient charts and, you know, all the machines, everything computerized, everything available they discover finally, and you've got 16 murders in the last six months. So we'll never know exactly...

DAVIES: It could be hundreds.

GRAEBER: According to some psychological profilers that have intimate knowledge of this case, it's likely hundreds.

DAVIES: Well, Charles Graeber, thanks so much for speaking with us.

GRAEBER: Thank you, Dave.

GROSS: Charles Graeber spoke with FRESH AIR contributor Dave Davies. You can read an excerpt of Graeber's book, "The Good Nurse," on our website, freshair.npr.org. Transcript provided by NPR, Copyright NPR.