US teen accused of trying to murder her brother's girlfriend

Warning: Graphic content

Kali Jade Bookey's sweet, elfin features radiate innocence in her Facebook and Instagram pictures.

She doesn't look like the kind of kid who would beat another girl to a pulp before repeatedly stomping on her body, choking her, smashing two glass bowls over her head and then using the broken shards to slit her throat.

According to US prosecutors, that's exactly what 14-year-old Bookey did last Thursday when she allegedly tried to murder her brother's girlfriend Halle Hickman, 15.

The assault, which lasted between three to four hours and opened with Bookey allegedly smashing her fists into Ms Hickman's head up to 30 times, was so brutal she will be tried as an adult.

Authorities claim Bookey told the victim she'd been planning the attack for a week and a half, cycling 17km to her New Richmond, Wisconsin home and tracking her family's movements in order to establish when the teen would be alone.

"I'm a psychopath," Bookey allegedly told Ms Hickman. "You're my first kill."

Ms Hickman told police that after Bookey slit her throat, she asked if she preferred to "die right now" or "bleed out", the New Richmond Times reported.

She chose the latter, claiming Bookey then told her to "have a nice afterlife" before leaving the scene.

Her mother Carrie later told The Eau Claire Leader-Telegram her daughter had given "no signs" she was planning the attack.

"There's a girl alone in the house"

Documents tendered to court by the St Croix County Sheriff's Office state that at around 9.30am, Bookey called police to report an attempted abduction.

They arrived to find Bookey with swollen and bruised hands and cuts and scrapes on her legs.

The teen told deputies she was attacked by two masked men armed with a knife while riding her bicycle. She claimed she got rid of the men by telling them there was a girl at home alone in a nearby house and giving them the address, the Leader-Telegram reported.

When police arrived at the home, they found Ms Hickman was lying on the floor bleeding heavily from the face and neck - but conscious enough to tell her rescuers that it was her boyfriend's sister, not strangers in ski masks, who had done this to her.

Police say Bookey confessed when they confronted her, telling them she blamed Ms Hickman for coming between her and her brother Michael, 16, and that she resented "how happy she made him".

She insisted her intention was never to kill Ms Hickman, only to "scare" her into moving away.

Bookey told the officers she'd set off for Ms Hickman's home on her bike at around 4am. She donned gloves before entering the house and making her way to Ms Hickman's bedroom.

The victim woke up to Bookey's gloved hands clamped over her nose and mouth in an apparent attempt to suffocate her, The New Richmond Times said.

Police claim Bookey admitted to punching Ms Hickman in the face 20-30 times, breaking two glass bowls over her head and cutting at her with the broken shards.

During the second hour of the attack, Bookey agreed to Ms Hickman's request for a glass of water but warned her she would "slit her throat" after she drank.

The teen later claimed she'd called police to get the victim help and only made up the abduction story to explain her own injuries.

Victim Halle Hickman, 15, pictured in hospital the day after her boyfriend's sister allegedly tried to kill her. Photo / Facebook

"Just shocked my sister would do it"

St Croix Chief Deputy Scott Knudson said Ms Hickman was lucky to be alive given her extensive injuries.

"If we didn't find her when we did, I think there was the potential for them to be fatal," he told The St. Paul Pioneer Press.

Ms Hickman, who uses her boyfriend's last name on social media - an increasingly popular trend among lovestruck teenage girls - remains in hospital under guard.

Michael Bookey posted a message to Facebook over the weekend after a photograph of his battered girlfriend started circulating on social media.

"She is very calm, and she is not at all shaken by it, just shocked my sister would do it," he wrote, adding the pair planned to get married.

"She says she loves her scars because they look cool, and she's only upset that her favorite (sic) dress got ruined."

"As she was bleeding to death on her floor, she sent me a message asking to have Bookey on her tombstone instead of her last name."

Kali Bookey's Facebook account has been deleted after it was swamped with abusive messages. Her mother Carrie was also targeted after she told local media her family was "very sad" and that Bookey had shown "no signs" she was planning the attack.

Others have leapt to their defence.

"They are a good family," a woman claiming to be a family friend told Heavy in an email after contacting the website with her concerns they were being unfairly trolled.

"They are a good family. They love their kids. They're still married. They know what their kids are doing and who their friends are. Our sons have been friends for years.

Bookey's mother "teaches zumba in town at the centre. I take her classes mon and weds (sic) at the centre. She's positive, full of energy. She is heart broken over this. And they DID NOT see it coming .... People are blasting their parenting. They are wrong."

Animal lover: Kali Bookey in a post to her Facebook account, which has since been deleted. Photo / Facebook

Is she really a "psychopath"?

Kali Bookey has been held without bond at a juvenile detention centre since her July 28 arrest.

She has been charged as an adult with attempted first degree homicide, which carries a maximum penalty of life.

But is the 14-year-old really a 'psychopath', as she so chillingly declared to her victim?

Probably not, according to leading Australian forensic psychologist Luke Broomhall.

While it was impossible to be 100 per cent sure with knowing Bookey's history and the full details of her alleged crime, psychopathy was not officially diagnosed in children under the age of 18, he said.

"Any behaviours in a child that might look like psychopathy could be caused by a number of different conditions or circumstances," Mr Broomhall said.

"However, hallmark features of adult psychopathy, the callous unemotional traits, have been observed in children. The key question, which can only be answered by thorough assessment, is whether behaviour is a one-off reaction to a specific situation, or represents a pattern of behaviour over time.

"Whilst Bookey self-proclaimed to be a psychopath, it does not mean she is one. There are other developmental disorders or mental health problems which might lead to the specific suspension of empathy required to carry out such a brutal attack."

St. Croix County Circuit Court Judge Eric Lundell refused an application by Bookey's lawyer for the teen to be released into her parents' custody.

Bookey is due back in court for a preliminary hearing on August 8.