Just as Deadly: The Psychology of Female Serial Killers

by Marissa A. Harrison

You've heard of Ted Bundy and John Wayne Gacy. But have you heard of Amy Archer-Gilligan? Or Belle Gunness? Or Nannie Doss? Women have committed some of the most disturbing serial killings ever seen in the United States. Yet scientific inquiry, criminal profiling, and public interest have focused more on their better-known male counterparts. As a result, female serial killers have been misunderstood, overlooked, and underestimated. In this riveting account, Dr. Marissa A. Harrison draws on original scientific research, various psychological perspectives, and richly detailed case studies to illuminate the stark differences between female and male serial killers' backgrounds, motives, and crimes. She also emphasizes the countless victims of this grisly phenomenon to capture the complexity and tragedy of serial murder. Meticulously weaving data-based evidence and insight with intimate storytelling, Just as Deadly reveals how and why these women murder―and why they often get away with it.

Genres: Nonfiction, True Crime, Psychology, Audiobook, Crime

280 pages, Paperback

Published February 13, 2025

Reviews

[Elaine · Rating 3 out of 5]

Thank you to NetGalley for an ARC of Just as Deadly.

As a fan of mysteries featuring fictional murderers and serial killers, the female serial killer has always fascinated me, mainly because they are rarely discussed, studied, and acknowledged.

The author's extensive research draws intriguing parallels and differences between male and female serial killers, taking into account personal, social, economic, and traumatic contexts.

I enjoyed how the author wove real life stories of female serial killers and dissected their personal histories, explaining why they committed their heinous crimes.

Not surprisingly, there are glaring differences between male and female serial killers, and more studies (much more
This was a fascinating read, though not for the faint of heart.

[Alexandria Brown · Rating 4 out of 5]

I love diving into the psychology of why people do things, and I think female serial killers haven't really been explored as much as their male counterparts. If you're into psychology and the background on true crimes, this is the book for you!

Thank you to the publisher and NetGalley for the eARC!

[Rachel · Rating 3 out of 5]

I received an eARC of this book through NetGalley in exchange for an honest review.

This was a fascinating and well-researched read. Most of the female serial killers I was familiar with prior to reading this book weren't from the US and often worked in teams with a man, so this book shone the light on crimes committed by women alone in the US that I hadn't previously heard of. I appreciated the multi-faceted approach toward the history of FSKs and their differences from MSKs. I also loved that the author repeatedly stated that she wasn't diagnosing individuals and emphasized the fact that most folks diagnosed with ASPD, have a history of trauma, or have psychopathic traits don't go on to be serial murderers. There's also a good focus on not sensationalizing the killers' crimes and instead focusing on the picture as a whole as well as the impact on victims and their families.

The only downside for me is that it's a bit data-heavy at times for my personal preference. I definitely want the information to be data-driven and to be included in the book in some way, but sometimes it was a little much and made the book dry. It felt more like a really long research paper than an engaging non-fiction book, so I wouldn't have minded some of the numbers to be included in an appendix for perusal if the reader wanted to see the standard deviations, etc.

Overall this was a very comprehensive read and I learned a lot!

[Rebecca Hill · Rating 4 out of 5]

Female serial killers are not new - but talking about them hasn't been as prevalent as some of their male counterparts. This was an amazing book, laying out some of the female serial killers. I was familiar with many, but there were a few that I wasn't aware of.

Great overall, and enjoyable! For those who enjoy true crime, this will be a good read.

[Susannah · Rating 4 out of 5]

Fascinating study of female serial killers in the USA. Looking at motives, psychology, influence of mental illness, how female serial killers differ from male serial killers in how they commit the crimes, types of victim etc. I really liked how case studies of specific serial killers were woven into the narrative and more scientific data to illustrate certain points. I would say towards the end it was very focused on neuroscience and psychology which I did not like as much as it was more information than I really wanted or needed and it was less accessible. However this is not a true crime book it is an academic study so it is worth knowing this before reading if this is not for you.

[Leah Efferson · Rating 5 out of 5]

I LOVED this book—it was a good combination of research and case studies to supplement the research. The differences between male and female serial killers are fascinating and important for prevention and detection. The only thing is the book became repetitive towards the end—it seemed there was not enough information to fill an entire book so some repetition was used.

[Sara · Rating 4 out of 5]

really good book. although sometimes there was too much data, in the end it made me discover how the brain of a serial killer works. it also claims how over the history only male serial killers’ brains have been studied and how female are just as deadly.
I really recomend it

[Annarella · Rating 4 out of 5]

Serial Killer are often a sort of pop murderes but there's not a lot of books about female SK nor books that talks about the crimes and the culprit without turning them in sort of antihero.
A well written and informative book.
Recommended.
Many thanks to the publisher for this arc, all opinions are mine

[Elizabeth]

Just as Deadly by Marissa Harrison takes a look at the mostly unexplored psychology of the female serial killer. Most chapters are started with the story of a female serial killer, of which I was only familiar with a few, before going into the deeper topic of that section.

While most questions about this demographic are as of yet unanswered, it was certainly interesting to see what the author and her team have mapped out in comparison to male serial killers. I'd recommend this to people interested in true-crime.

[Becki D · Rating 5 out of 5]

Highly recommend. Very well researched and interesting perspective of evolutionary psychology

The only thing I disliked was so many abbreviations.

[Staphy · Rating 4 out of 5]

RTC

[Janalyn, the blind reviewer · Rating 5 out of 5]

If you think only men can be serial killers or mass shooters then you need to read this book. It seems for every male stereotype murderer there’s a female in Lou of the deadly Canadian pig farmer we have the farm owning black widow Belle Gunness Think we don’t have a mess murderer meet Amy Gilligan and the list goes on and on from Dana gray to the twisted Tammy Kennis they have some truly ruthless women in this book. Dr. Marissa a Harrison has done a wonderful job with each case study in the book and she even uses her talent and experience to try and answer the question why do we like serial killers? This is a lot more than just your average True Crime story with impeccable insight and great riding instead of just answering who and how she also answers why I truly enjoyed this book and wish I would have had three more just like it. I received this book from NetGalley and the publisher but I am leaving this review voluntarily please forgive any mistakes as I am blind and dictate my review.

[Meg · Rating 3 out of 5]

Interesting book on female serial killers. The author gives plenty of examples of crimes committed by women. It was the first book I read about this problem written by a respectful psychologist. Highly recommend it to people interested in this field of criminology.

[Brandon Westlake · Rating 5 out of 5]

I teach high school, and true crime is all the rage. My students watch every miniseries that streams on serial killers and unsolved murders, but I doubt any of them can mention most of the women Marissa Harrison describes in this book. I felt like the usual serial killer books go through the same arc. Screwed up childhood, bad parental relationship. Denied sex somewhere along the line. Not with these women. Her book is comprehensive in looking at all aspects of female killers, and does a really great job comparing their work to that of men. A case could be made that while not as gruesome as their male counterparts, some of these women's stories are much more disturbing.
I'm glad this book has been written, as it always is said that these acts are committed by men. Maybe our propensity for bloody killings has made us overlook or ignore those committed by women.

[Kate · Rating 5 out of 5]

A couple of notes first: This book is 50% the book and 50% the sources. This is annoying only because I would have liked to keep reading way more information on this topic. It's actually kind of fitting though considering the whole reason this book exists is because there is basically zero information on this topic as it is. That being said the 50% sources makes for an extremely well researched book that will hopefully lead to more studies ASAP.
Marissa A. Harrison gives us a wholly original book on the psychology of female serial killers. They make up such a small percentage, but why? Are the less deadly or are they smarter and thus not getting caught? Does it have to do with general unwillingness of people to think women are incapable of heinousness? Personally, I think it's a combo of all of these things. They don't kill in the same way, they take longer to be caught (if they ever are) because of this, plus people often don't think women capable of these acts.
The amount of research in this book is incredible and so interesting to read about. MAH addresses multiple things that could be the reason for the hows and whys of female serial killers. I am hoping this will lead to some new profiling as well since the only one we have is for male serial killers...who kill in drastically different ways and for different reasons.
True crime fans, serial killer buffs, thriller/horror fans - read this one.
The only thing I would say I didn't like is that MAH mentions her published study multiple times. I would LOVE it if the actual study was included at the end to read through. There are links to all sources, but it would be nice to be able to read that one in the same book.

Thanks to NetGalley for my copy to read in exchange for an honest review!

[Cristi Marashi · Rating 2 out of 5]

DNF
The book was off to a promising start, but a tedious and long read. Not quite 40% in, the author starts talking about male serial killers and lost me. That isn't what I was looking for in this particular book
The author's writing style is also quite informal, which one one hand is nice because it makes it easier to understand what she's talking about, but on the other hand her train of thought seems to jump from place to place...like this section about the male serial killers to illustrate the difference between male and female serial killers...but the sections on the male serial killers are much longer and her point could have been illustrated in the first example about John Wayne Gacy. I like the idea behind this book, but from what I read it wasn't well excuted.

[Katie · Rating 2 out of 5]

This book.

Okay. I'm a huge true crime afficionado. Gotta have my daily dose in the form of podcasts, YouTube videos, and/or the written word. The vast majority of the material covered across all these forms of media and among the various creators offering it has certain patterns. Most killers are (cis) men, and most victims are (cis) women or children. Mostly in the English spheres these people are all white and Western.

So, I was very excited to read a text about "female" serial killers or FSK, especially an academic one. And it was fascinating, even when it was enfuriating.

The author is an evolutionary psychologist. Now, I don't have the space to go into it, but that subset of scholarship has experienced a lot of criticism from all fronts. Unfortunately, two major criticisms–lack of falsifiability and bias due to modern sociocultural norms–raise their heads over and over in this text. Moreover, the author makes a ton of leaps in logic, generalizes from very little evidence, extrapolates findings from other areas, etc. She leans heavily on scientificese, e.g., "To be scientifically fair ..." in short, rather poor scholarship overall ... and if I'm being really critical, I'd even go so far as to call it merely "the guise of scholarship."

The author's basic premise is that FSKs and their "male" counterparts, MSKs, are fundamentally different. Hm! In short, her argument is that FSKs are in it for the money and MSKs are in it for the (sexual) gratification. She has a little note about sex and gender, but it seems to be more of an aside to preclude us pesky naysayers. Here's a quote that wraps it up: "women and men have different behavioral tendencies due to evolved psychological processes, largely based on differences in reproduction." Just a statement, not a fact. She further muddies the waters with terms like "biopsychosocial." She frequently bends over backwards attempting to make her binary point, even while she contradicts herself at several junctions. Yes, there's more than a flavour of biological essentialism going on here.

When we go into the details, we get a slightly different story. Aileen Wuornos, for instance, was abused as a child and "learned violence as a coping skill," i.e., traumagenic development. Others had mental health and/or drug dependency issues (and I write these with great hesitation, but they are factors that she notes). But over half of FSKs had "hedonistic" objectives, including for entertainment, for the thrill of it, to protect their own interests, and even for personal comfort. I'm not quite sure how we end up with the "money vs. malice" dichotomy, but we do.

The author relies on small samples and a lot of extrapolation. The tables comparing FSKs and MSKs at the end are telling. Apparently almost all serial killers are from the US! Who woulda thunk it? She also writes about class but not a peep about race/ethnicity. I won't go into the details, but take a look and you might find a meta-level theme when it comes to the selection of these factors: the bias of the author at play.

For some reason, we also get the author's thoughts on other irrelevant matters. At one point she writes that "consuming true crime media may literally be addictive." Receipts, please. She also dismisses major problems like the infodemic, writing that "some people feel" that misinformation is everywhere and a real problem. Actually, her colleagues working in that area have shown conclusively that it is, with a lot of data from around the globe, over time and across sites, through a variety of research methods–unlike her. To be fair, she acknowledges and even seems surprised at how little she had to go on, to the extent of having to write so much about MSKs (and there was really too much on that front): "Within a book aimed at telling the stories of female serial killers, I certainly did not set out to write so much on John Wayne Gacy." Well, we certainly didn't expect to read so much about him, either!

What I really got out of this text was a moment for self-reflection as a true crime enthusiast. At one point, the author talks about how cases are too often treated as commodities, even as a certain brand of entertainment. She quotes Erika Magan: "True crime keeps the pain alive." And also Maggie Larson, with true crime programs that go too far being "the ultimate sense of entitlement to others' lives." This brought to mind the podcaster in Kirsten Miller's The Change. I found myself unnerved and moved to evaluate my reasons for engaging with this material. At the same time, I found myself revisiting my appreciation for the current shift towards victim-centric true crime coverage, especially in creator spaces. Some podcasts, notably Canadian True Crime, go out of the way to check in with victims and families and communities, not only centring their experiences and perspectives but also deciding that it's informed consent or nothing.

In the end, I find myself disappointed and a bit disturbed—and not because of the murders and murderers.

Thank you to Cambridge University Press and NetGalley for the advance copy.

[Tyler · Rating 2 out of 5]

I considered giving this 1 star but that would be too cruel to this. Just the fact that I was considering it should tell you something though. I can't give it 1 star simply because there are parts I enjoy. Being a psychology hobbyist for around 5 or 6 years at this point, I've read a lot, learned a lot, and seeing how the extremity of serial killers relates to what I understand from the psychology of men and women is interesting. That makes me believe that what Harrison writes is grounded in some truth. Some of the statistics were also interesting to me, such as the declaration that a lot of male serial killers have mental illness, but fewer female ones do. There are moments like that where I go "ahh, neat."

Harrison says early that she's not a writer. She's not going to fluff things up. I understand, that's cool. She makes the language simple, which is good, but you feel that she's not a writer. That's because she is sometimes repetitive to the point of redundancy and doesn't connect things that well. But even then, the writing is breezy and fine, and she likely was a little too hard on herself in this regard.

My problem is that she spends a good chunk of the last, say, half or so, talking a lot about male serial killers. There are moments where this is appropriate; when she's discussing stats, it makes sense to compare MSKs and FSKs. But telling me stories about Gacy is unnecessary. We didn't need detailed retellings of their life stories because we have those elsewhere, and this book isn't supposed to be about that. Mention MSKs for comparison, say a little bit, move on. That's my biggest issue with the book and the reason I can't up it to a passing grade. "The Psychology of Female Serial Killers" is a little misleading, all things considered.

[kylie · Rating 2 out of 5]

For a book about women committing murders, this talked a lot about men committing murders. As if they're the default, and everything female serial killers do or don't do is in relation to male serial killers' behaviors and motives. (Obviously, men kill more, so comparing is noteworthy, but it seemed that the most gruesome parts and deepest dives of the book were about notable MSKs.)

Also, it's stated about halfway through that a major feature of women serial killers is their motive, namely financial gain versus sex. While I agree this is true (not that my non-credentialed ass needs to agree), I think a huge factor went unsaid. Why might women kill for resources? Perhaps because historically the patriarchy has made it so women get less and/or only get resources through connection to a man. Even now, women are still fighting the gender pay gap and being passed over completely in the workforce for mediocre men. That's not to say that the answer is ever murder, but it does make you think about how vulnerability can lead to desperation can lead to a certain type of person thinking they've cracked the code on how to get what they need (and then some).

Thinking about it more, I would also argue that the primarily male serial killer motive is actually power, not sex. Why? They are 1)primarily lower class and only high school educated, 2) killed mostly adults, and 3) you don't have to kill someone for sex. Not to mention, generally speaking we've all agreed that rapists get off on the power. It's a power move. It's not about sex. Ergo, even if sexual assault also occurs, the murder seemingly was about having power, and what feels more powerful than control over life and death?

Anyway that got dark.

[Alex · Rating 4 out of 5]

As you may know from my Goodreads reviews, I know a little too much about murder, so a lot of the names in here (Nannie Doss, Belle Gunness, Jane Toppan) weren't unfamiliar to me at all. I recognize I know a little bit too much about these kinds of things. Still, this was a great study about female serial killers, their motives, and how they differ from male serial killers. I was surprised by how little previous literature there was on the subject, so Harrison and her team filled a gap here for sure.

The main thing that stuck out to me was "male serial killers are caught, female serial killers are detected." FSKs are more likely to kill people they know or that are in their immediate circle, closer to home, and using less violent methods. It means that it can be way harder to catch unless you are paying attention, but women (especially older women) can slip under the radar more easily. The profile tends to be a lot less showy than their male counterparts. Harrison's study includes 64 documented female serial killers from the 19th through 21st centuries -- it can feel like that number is low, but when you consider that serial killers each have at LEAST 3 victims, that's a lot of lives lost at the hands of these women. That is, of course, DOCUMENTED serial killers, meaning there are probably more women out there who have committed crimes but were never caught due to various factors.

There's nothing overly sensational in here as it's an academic volume, and it's a great primer for anyone who has an interest in the topic.

[Anne S · Rating 4 out of 5]

This is a book about female serial killers. They are usually in the background and not as noticeable because people do not believe that females can be deadly. I liked how she wrote about the female serial killers (FSK) based on credible sources. The one annoying thing she did, was say "This is a serial killer" each time she labeled a person a serial killer. I think that we got the hint when the book was about serial killers.

There is not too much written about the serial killers who were female, only to say that most of them were caregivers who either killed (their children), older people, people in nursing homes, etc. Women serial killers are detected. Male serial killers are discovered. The main reason is that the victims who were killed by females were thought to have died of natural causes!

"Experts have a three baby rule". When the first baby dies, it's considered SIDS. If a second baby dies, (without a known cause), it's considered undetermined. If the third baby is in the same family, they suspect homicide! there was one woman who had 9 babies die in the same family (Mary Tinning). One would think that after the 3rd or 4th baby died, someone would have gotten a clue!

If you are into the psychology of why people do what they do, this is the book for you.
If you are not into clinical discussions, then this book might be too deep or technical.

[Nicki Kendall · Rating 4 out of 5]

Thanks to NetGalley for the the ARC in exchange for a fair an honest review. This was a fascinating read. Usually we get a lot of male serial killer books and what makes them tick and not many that delve into female serial killers, their motivations and how they differ from male serial killers.
The author's extensive research draws intriguing parallels and differences between male and female serial killers, taking into account personal, social, economic, and traumatic contexts.
Whilst a lot of the well known serial killers both female and male were discussed, as to be expected, the book also raised some other female serial killer cases that I was not familiar with. It was very interesting to learn more of the different motivations that drive both male and female serial killers and also the different methods of killing that each sex more frequently employs. A fascinating read. A must have to add to your True Crime TBR. #justasdeadlythepsychologyoffemaleserialkillers #marissaaharrison #netgalley #goodreads #litsy #thestorygraph #tea_sipping_bookworm #bookqueen #bookstagram #truecrime

[Lois · Rating 4 out of 5]

A bit over repetitive and reliant on contrasting information on male serial killers at times, this is nevertheless an excellently researched and written book. It shows commendable moral integrity throughout, with Harrison always expressing empathy for victims whilst trying to determine contributive factors to female serial killers, and taking pains to emphasise that no factor acts in isolation nor is ever guaranteed to result in an FSK. This is excellent criminology that never resorts to, an ultimately quietly rebels against, the most hideously indulgent aspects of "true crime" phenomena.

[Alicja · Rating 3 out of 5]

Surprisingly low but it was way less interesting than I expected. I had a feeling the information was repetitive but I can't blame the author for that as she said many times that there is not much valid data available about FSKs.
My favorite part and a 5 star moment was the part with comparison of FSKs and MSKs - the rest was a big meh to me.

[Cait Nowakowski · Rating 4 out of 5]

Very interesting look at the psychology of female serial killers and how they differ from male serial killers. I got a little bogged down towards the end but really enjoyed the overall findings and message. The breaks in chapters with different cases of female serial killers was a nice way to pace this book and helped keep me from feeling overwhelmed with the science.

[Cheri Swalwell · Rating 4 out of 5]

This book was eye opening to the psychology behind women killers. They aren't as suspected as readily because they are women, mothers, wives, but they can be more deadly or more evil than their male counterparts. Interesting read, and I'm still thinking about some of these cases and shaking my head.

[Denn Chacón · Rating 3 out of 5]

Loved that it was basically a scientific article, but a little bit more approachable, still it had a lot of rich information regarding statistics. I stiff feel a biiiiit troubled about some parts that I found too...let's say black or white regarding sex, gender and such, but it was an interesting read since there's not much detailed books about FSK

[Nichola · Rating 3 out of 5]

There is a reason you state your theoretical framework upfront, so that people like me who think evolutionary psychology is a bag of shit don’t get stuck reading an entire book.

Also I know academics are used to initialising and creating acronyms for everything but stop. It’s inaccessible and unnecessary. You are actively losing meaning.

And too much focus on male serial killers

[Teresa · Rating 2 out of 5]

Links

This isn't really facts but where to to find the information you might want. I bought the book to read the theories and get the psychology. Not links. Gave two stars instead of one because at least I know where to look I guess.

[Ariana Gleason · Rating 4 out of 5]

i loved this book! very interesting to read about the psychology on female serial killers vs male serial killers and the role society, genetics, and environment have on them and the differences between the two.