How can you fall in love with someone who murdered 49 people?

Serial killer Alexander Pichushkin and Natalya, the woman who fell in love with him. Photo / AP

Warning: Content may disturb some

It's one thing to be attracted to bad boys and alpha males. But it's another thing entirely to fall in love with one of the world's most notorious serial killers.

Natalya, the pixie-haired woman pictured above, began writing letters to Alexander Pichushkin in 2007 when he was sent to jail for murdering 49 people.

(As a side note Pichushkin, 42, isn't sure how many people he actually killed. What he does know is he was trying to get to 64 deaths in total, to match the number of squares on a chessboard. Hence his moniker "the chessboard killer").

Natalya, a 29-year-old shop worker from Nyagan, central Russia, began writing to Pichushkin as soon as he entered prison.

Now, despite the fact that they have never actually met and he will spend his life behind bars, they are engaged to marry. He proposed in a letter. She has taken his surname and has a tattoo of him on her forearm.

Although she would ultimately like to have a baby with him, she says they have agreed for her to find another man to have children with because he will be in prison until he dies.

To get a measure of Pichushkin's appetite for murder, consider this: he has killed more people than Jeffrey Dahmer, Jack the Ripper, and the Son of Sam combined.

He preyed primarily on elderly homeless men and lured them into Moscow's Bittsa Park with the promise of free alcohol.

He hit his victims in the head repeatedly - usually with a hammer - and in what became his trademark, he would push a vodka bottle into the gaping wound in their skulls.

He was arrested in 2006 after police discovered a metro ticket on the body of one of his victims. They reviewed surveillance footage at the train station and saw the victim walking on the platform with Pichushkin just hours before her death.

In an interview after his arrest he said he could not go on living without killing people.

"For me, a life without murder is like a life without food for you.

"I felt like the father of all these people, since it was I who opened the door for them to another world," he said.

He was sentenced to life imprisonment in the Arctic north of Siberia with the first 15 years to be spent in solitary confinement.

So it's little wonder that the frequent letters from young Natalya became such a focal point.

In fact, it's reported that he has around 80 women writing to him.

But Natalya is the one he has proposed to.

Alexander Pichushkin in court. Source / AP

She says, "I will always be there for my maniac," and insists that her love is a changed man.

"I do not share the interests of the old Pichushkin," she said in an interview last week with The Siberian Times.

She claims that authorities have been blocking their letters and she hasn't heard from him in two years.

"Employees of the institution where he is serving his sentence do not want us to communicate," she told reporters.

"I don't know what have I have done, or why they do this to me. He is my everything. I have nothing in this world without him. I'm dead without him."

So how can it be that this woman - and 80 others - are so enamoured with this particular serial killer?

Psychologists would say that Natalya is suffering from hybristophilia, or "Bonny and Clyde syndrome" as it's often referred to (we wrote about it on news.com.au earlier this year).

Basically, grisly crimes turn people with hybristophilia on. It's a fetish of sorts.

Psychologist Katherine Ramsland has written extensively about serial killers and attraction and has looked at the different reasons women gave for loving serial killers.

"Some believe they can change a man as cruel and powerful as a serial killer. Others 'see' the little boy that the killer once was and seek to nurture him.

"Some mental health experts have compared infatuation with killers to extreme forms of fanaticism. They view such women as insecure females who cannot find love in normal ways or as 'love-avoidant' females who seek romantic relationships that cannot be consummated.

"Yet while this might be true in some cases, several devotees have been strikingly beautiful, educated, and even married. A few have been lawyers, psychologists, or judges."

She wrote that a "biological impetus operates apart from logic".

Alexander Pichushkin looks on from behind a glass security cage during the first day of his trial in Moscow in 2007. Photo / AP

"Primate research finds that females prefer the larger, louder, more aggressive males who show clear markers of their maleness," Dr Ramsland says.

"In humans, then, certain women might sense in an aggressive male a larger-than-life companion who can deliver more than an ordinary man could. Through him, she subconsciously perceives, she gains status and protection.

"Then there's the notion of the 'perfect boyfriend'. She knows where he is at all times and she knows he's thinking about her. While she can claim that someone loves her, she does not have to endure the day-to-day issues involved in most relationships. There's no laundry to do, no cooking for him, and no accountability to him. She can keep the fantasy charged up for a long time."

This notion of trying to find the "perfect boyfriend" who can be kept at arm's length could ring true in Natalya's case. She started writing to Pichushkin after the end of a violent marriage.

"My husband was beating me and cheating on me with a friend of mine," she explained in her TV interview.

"I was trying to forget about it by getting myself drunk, sometimes it was going on for days, weeks, months. Everything changed when they showed [Alexander Pichushkin] on TV".

There are a surprising number of women who show signs of hybristophilia.

The courtroom at Ted Bundy's trial was apparently filled with women. Some love-struck ladies photoshop images of themselves embracing hardened killers. And young Afton Burton, pictured below, desperately wants to marry Charles Manson.

Joy Krause is someone who knows a bit about the topic of women with a fetish for serial killers. She directed the film Serial Killer Groupies (which you can view below) and told The Huffington Post in 2014 that the people who have committed the most heinous crimes are the most popular.

"They have thousands and thousands of adoring fans," she said.

"I've spoken to dozens and dozens of women who have relationships with men on death row. Some are serial killers. I've talked to women first hand and I've learned (their reasons).

"There's this thing about being with an alpha male for instance - it's kind of a bizarre twist that an alpha male is strong, powerful, but to think of someone attracted to this personality ... to think that they can be protected by an alpha male, is a bizarre twist."