A Miami man facing charges that he killed his former girlfriend then dumped her body in Delray Beach told detectives that the woman “wasn’t being herself and he had to kill her,” according to an arrest report.

John Eugene Chapman allegedly admitted to Palm Beach County Sheriff’s detectives that he stabbed Vanessa Carmen Williams Bristol multiple times after they got into an argument in the woman’s vehicle. Chapman said he punched Bristol several times in the head then “snapped” when he saw the victim reach for a weapon.

The arrest report states that Bristol spoke with Margate police on April 16 about a “dispute” she got into with Chapman. Bristol told officers she had picked up Chapman in Cape Coral because he did not have a vehicle.

On April 18, Bristol and her mother made arrangements to have dinner. This was the last time the mother heard from Bristol, according to the arrest report.

On that same day, Chapman showed up at his girlfriend’s house in Cape Coral with a bloody shirt, according to the arrest report. Chapman told his girlfriend he had been involved in a fight. Chapman took a shower, grabbed his belongings and left in a Ford F-150 that belonged to Bristol. The vehicle was found abandoned in Fort Lauderdale.

On Monday, agents from the U.S. Marshals Service arrested and charged Chapman with fleeing and eluding, possession of cocaine, driving with a suspended license and probation violation — all unrelated to Bristol’s murder.

During an interview with sheriff’s detectives on Tuesday, Chapman said he got into an argument with Bristol on April 18, when he pulled the woman’s hair and dragged her across the front seat of the Ford F-150 so he could take the truck, according to the arrest report.When Bristol reached for a knife, Chapman said he “went into robotic mode” and began stabbing the victim “until he realized she was dead,” the report said.

According to the arrest report, Chapman acknowledged killing Bristol at the entrance of the Palma Vista development in suburban Boca Raton then dumping the body and the knife in a shallow ditch in unincorporated Delray Beach.

Chapman, 25, is being held at the Broward County Jail and is awaiting extradition to the Palm Beach County Jail, according to officials at the Palm Beach Sheriff's Office. In addition to first-degree murder, Chapman is also charged with grand theft for allegedly stealing Bristol’s vehicle.

Florida Department of Law Enforcement records show that Chapman has been arrested 12 times since July 2010. He was sentenced to a year of probation on April 11, 2014 after being arrested for cocaine-related charges.

Chapman and Bristol, 28, have a child together, according to the sheriff’s office.