Wheeler-Weaver, 23, is accused of brutally killing three women and attempting to slay a fourth back in the fall of 2016 - but 20-year-old college student Sarah Butler would be his final victim, prosecutors claim

One of the victims of a New Jersey man's alleged 2016 killing spree text him just hours before she was murdered asking the then 20-year-old if he was a serial killer, prosecutors have revealed.

Khalil Wheeler-Weaver, now 23, is accused of brutally killing three women and attempting to slay a fourth back in the fall of 2016 - but college student Sarah Butler, 20, would be his final murder victim, prosecutors said.

Less than two hours before they met for the first time on November 19, 2016, the defendant searched the internet looking up information about date rape-drugs and homemade poison.

Prosecutors say he then solicited Butler for sex via the social media app Tagged, offering her $500 to go through with his request.

‘Wow,’ she responded to Wheeler-Weaver on the app. ‘You’re not a serial killer, right?’

Ten days later, Butler’s body was found in the Eagle Rock Reservation nature reserve covered by leaves and detritus. An autopsy would later show that she’d been strangled to death.

The details connecting Wheeler-Weaver’s cell phone searches, interests in deadly poisons, and his attempts to contact other women for sex were heard in a full day of testimony in Newark’s Superior Court on Thursday.

In addition to killing Butler, the 23-year-old is also accused of slaying 19-year-old sex worker Robin West and Joanne Browne, 33, while also attempting to kill another woman – referred to as ‘T.T in court documents – who testified against him at trial.

Investigators say the three murders - and fourth attempted case - were all sexually motivated.

Prosecutors say he then solicited Sarah Butler (above), 20, for sex via the social media app Tagged, offering her $500 to go through with his request

Wheeler-Weaver (seen in court last month) has admitted that he was with each of the murder victims shortly before they disappeared, but denies responsibility for their deaths. His attorneys say each of the victims ‘put themselves in vulnerable positions’ and said their client was fully cooperative with law enforcement throughout their investigation, which they argued is ‘not the conduct of a guilty individual’

Prosecutors say the accused purposely targeted young black women who turned to sex work to cope with mental health issues or homelessness. The reason, authorities say, was that he believed no one would notice if they disappeared.

‘They were viewed as somehow less than human, less valuable,’ Essex County assistant prosecutor Adam Wells said last month, according to NJ.com

Butler, who also worked as a lifeguard at the local YMCA and was a second-year student at New Jersey City University, was an exception to the rule, prosecutors said.

After she disappeared, her friends and family launched a sting operation that would eventually identify Wheeler-Weaver as the prime suspect and see him apprehended for the months-long crime spree that took place in abandoned houses and budget motels across northern New Jersey.

Wheeler-Weaver has admitted that he was with each of the murder victims shortly before they disappeared, but denies responsibility for their deaths.

His attorneys say each of the victims ‘put themselves in vulnerable positions’ and said their client was fully cooperative with law enforcement throughout their investigation, which they argued is ‘not the conduct of a guilty individual’.

On Thursday, prosecutors unveiled hundreds of pages of records detailing how Wheeler-Weaver used his cellphone to investigate how to create homemade drugs powerful enough to knock someone unconscious.

He also sought out instructions as for how to kill a person using household chemicals like bleach and ammonia.

Such searches included ‘How to make homemade poisons to kill humans’ and ‘What chemical could you put on a rag and hold to someone’s face to make them go to sleep immediately,’ court records show.

Prosecutors revealed last month that Butler’s parents, sister, and friends took matters into their own hands, by logging into her social media accounts to see who she’d been talking to in the hours before her disappearance (pictured: Victor Butler, father of victim Sarah Butler, comforts a woman during an appearance by Kalil Wheeler-Weaver in Essex County Superior Court, December 13, 2016)

In addition to killing Butler, the 23-year-old (shown in 2017) is also accused of slaying 19-year-old sex worker Robin West and Joanne Browne, 33, while also attempting to kill another woman – referred to as ‘T.T in court documents – who testified against him at trial

Wheeler-Weaver then sought information for ways to erase evidence of his search history, typing into one search engine, ‘If I erase all the contents and settings will it track?’, in reference to his cellphone’s location tracker.

Interspersed between the various searches, the defendant even inquired how to become a police officer, searching ‘police entrance exam practice test,’ on one occasion.

‘He doesn’t look like someone who would’ve done something like this,’ Essex County Assistant Prosecutor Adam Wells said at the outset of the trial, which began mid-October, NJ.com reported. ‘But you’re going to see the evidence that says he did.’

Wheeler-Weaver’s apparent killing spree is believed to have begun on August 31, 2016, when Robin West, a 19-year-old sex worker was last seen alive.

West, a Philadelphia native who had recently moved to Union Township and struggled with mental health issues, was days away from celebrating her 20th birthday when she vanished - alarming family members when she failed respond to their messages days after.

Authorities received a call of a fire at an abandoned house in Orange, NJ, on September 1. It was inside that they found the 19-year-old’s badly scorched body, which took nearly two weeks to identify.

When quizzed by police, Wheeler-Weaver said he had taken the girl out to eat on the day of her disappearance, but claimed he’d dropped her off at a different abandoned house two blocks away from where her body was found.

While investigators puzzled over West’s death for weeks, another local young woman disappeared in the meantime.

Joanne Brown had been grappling with homelessness at the time she was last seen alive, climbing into Wheeler-Weaver’s car before being reported missing in October the same year.

Two months later, a work crew found the 33-year-old’s lifeless body inside yet another abandoned home in Orange.

Wheeler-Weaver’s apparent killing spree is believed to have begun on August 31, 2016, when Robin West (above), a 19-year-old sex worker was last seen alive. Authorities received a call of a fire at an abandoned house in Orange, NJ, on September 1. It was inside that they found the her badly scorched body, which took nearly two weeks to identify

Joanne Brown (above) had been grappling with homelessness at the time she was last seen alive, climbing into Wheeler-Weaver’s car before being reported missing in October the same year. Two months later, a work crew found the 33-year-old’s lifeless body inside yet another abandoned home in Orange

Her nose and mouth were covered in duct tape, and she had been strangled to death with a jacket – which was still tied around her neck when she was found.

Days later, a terrified woman came forward to describe a traumatic encounter she’d just had with Wheeler-Weaver at a motel in Elizabeth. The unnamed woman, who at the time was 34, turned to sex work after becoming homeless.

Identified as T.T during the trial, the woman said she woke up in the back seat of her car with duct tape on her face and Wheeler-Weaver kneeling over her, clad in a ski mask, raping her and attempting to ‘choke her back to sleep’.

Eventually, T.T said she managed to remove the tape by ‘screaming and crying’. She convinced the defendant to take her back to the Ritz Motel in Elizabeth, where the pair initially met, under the ruse that she’d left her cell phone behind.

There, she raced into a room and locked the door behind her where she dialed 911 for help.

Still, months would pass before Wheeler-Weaver was arrested on attempted murder charges.

One week after T.T’s alleged encounter, Wheeler-Weaver met up with Butler in Orange. When the student failed to return home the next morning, her family called police.

Their worst fears were confirmed on December 1, 2016, when she was found dead in the nature reserve.

Another five days would pass before police brought Wheeler-Weaver into custody.

Prosecutors revealed last month that Butler’s parents, sister, and friends took matters into their own hands, by logging into her social media accounts to see who she’d been talking to in the hours before her disappearance.

On the controversial social networking app Tagged – which is regularly linked to sex crimes – they found her exchange with Wheeler-Weaver.

Prosecutors say the accused purposely targeted young black women who turned to sex work to cope with mental health issues or homelessness. The reason, authorities say, was that he believed no one would notice if they disappeared. ‘They were viewed as somehow less than human, less valuable,’ Essex County assistant prosecutor Adam Wells (above) said last month

Butler’s relatives then set up fake profiles on the site, promising to meet up with Wheeler-Weaver for sex in an in-person meet up. But when he arrived, he found himself face-to-face with police instead.

‘There are many courageous people in this case but we were particularly aided by the help of Sarah Butler’s family and friends who used her social media to help us in our investigation,’ Essex County Prosecutor's Office spokesperson Katherine Carter said.

In addition to Wheeler-Weaver’s search history, police were also able to contradict his story about the last time he’d seen West, with location tracking technology showing him present at the same house as to where he body was found shortly before it erupted into flames.

After driving from the scene, he appeared to return back to the neighborhood to watch firefighters tackle the blaze.

His call logs also show he was the last before to speak to Browne before she vanished. Authorities say he picked her up and brought her to the vacant house where she was found dead.

Data shows he spent an hour there before leaving her alone.

Wheeler-Weaver was finally indicted on three counts of murder, three counts of desecration of human remains, attempted murder, aggravated arson, aggravated sexual assault, and kidnapping, in February 2017.

A search of his home found two cellphones on the nightstand beside his bed, and a third hidden under his mattress.

‘I need to know what happened to him, what caused him to snap like this,’ Leroy West, the father of Robin West, told WHYY in 2017.

‘I’ve been face-to-face with him in court, and I’m looking at a handsome young man, and I’m thinking: ‘Why would you need to go out and track these young women and murder them?’

The trial is set to continue later this week.