A forensic psychiatrist has explained five reasons why some women are lured in by the sinister charisma of serial killers even after their sick crimes have been revealed.
From Ted Bundy, Charles Manson to Richard Ramirez, horrendous criminals have managed to gather a collection of admirers despite being locked.
London based psychiatrist Dr Sohom Das, 44, also makes YouTube videos about mental health for his channel A Psych for Sore Minds.
In one video he gave five reasons why men who commit the most violent crimes attract some women.
He explained: "I've mentioned Ted Bundy, but there are also other high profile murderers, including Charles Manson, Jeffrey Dahmer, and then Night Stalker Richard Ramirez, who was sent letters and gifts from women all over the world.
"To me, the Dahmer case is extremely shocking, because these pure, kind hearted women managed to look past the cannibalism...the sex offending, the dismembering, they even looked past his own sexuality and they still swiped right."
Dr Das also mentioned Chris Watts, who murdered his pregnant wife, and their two daughters Bella, 4, and Celeste, 3, in 2018.
He said: "Chris Watts received love letters and photos from female admirers...One even sent a photo of herself in a bikini to Chris Watts in prison."
Here are the five reasons Dr Das gives.
1. Psychosis
In one case a woman was in the grips of psychosis and thought she was communicating telepathically with a criminal.
She believed they were in a relationship even though the two hadn't met.
Dr Das adds: "And also, this is an extremely rare presentation so we can just sort of put it off to the side... I just wanted to give it an honourable mention."
2. History of trauma
A more common explanation is a history of trauma.
For these women, who have often been either physically or emotionally abused, its about repeating the cycle of abuse.
Dr Das says: "So they've either been physically, sexually and or emotionally abused by a partner or by their parents [and] they want to repeat this kind of cycle, either subconsciously or intentionally.
"And so unfortunately, these women tend to gravitate towards what's familiar instead of what's safe. And we see this phenomenon in victims of abuse.
"Sometimes they become abusers themselves, and...tragically some young girls who witnessed domestic violence as a child...pick abusive partners when they become adults themselves, partly because it's ingrained in them to see violence as a way of conflict resolution."
The fact their 'partner' is behind bars gives the women a sense of control, Dr Das explains.
3. Saviour complex
Often used as explanation as to why some women can be attracted to 'bad boys', here it's taken to the extreme.
Dr Das says the women can relish the challenge and "feel that they could save or transform the prisoner or the killer".
4. Idealised relationship
Another psychological aspect Dr Das brings up is the idea of the "perfect relationship".
If your partner is in prison you don't have "to endure the day to day issues that are actually involved in most relationships".
So no cooking, smelly socks left around or laundry.
5. Hybristophilia
The final psychological explanation is a condition known as hybristophilia, colloquially known as Bonnie and Clyde syndrome.
Dr Das explains: "I think it's very fair to say that some of these women do this because they...crave attention or fame."
It is a type of paraphilia, which is persistent atypical sexual attraction, urges and fantasies involving objects, activities, or even situations.
Dr Das points out that it's not restricted to a particular social or economic class.
He says: "I've heard there are examples of educated women with careers, including lawyers and barristers, who fell for or married killers who will either be sentenced to death or will never be released."
In his opinion, a lot of it is "connected to the celebrity worship, and some women have done this very overtly."
He continued: "And this is all kind of psychologically linked, in my opinion, to conflating being famous and being infamous.
"And I think that's a relatively recent phenomenon, something that we've seen grow hugely in front of our eyes for the last couple of decades...we see it in reality TV stars, they often become famous just for the sake of fame. And I think that the public feel this and we're partly to blame".
What's in it for the serial killers?
But these relationships go two ways.
For the serial killers, it's often the attention they crave.
Dr Das explains: "I think it's fair to say that many of them are psychopaths and narcissists, and those groups of people often attract women because they have the ability to be charismatic and to charm vulnerable people who are susceptible to this kind of manipulation.
"Narcissists are very grandiose, and they're very entitled to things like sex and relationships.
"Psychopaths are the same so they have this inflated self esteem, but they're also very charming and they're calculating and they're quite devious, so they're very good at knowing...what to say, to make the women feel special, to feel loved to feel privileged to feel that they're part of like, some sort of special bond."