A South Carolina man has confessed to four murders after a missing woman was found chained in a shipping container on his rural property. The woman’s boyfriend was found dead of multiple gunshot wounds nearby.

Police arrested Todd Kohlhepp on Thursday in the missing-persons case of Kala Brown, 30, and Charlie Carver, 32, who disappeared from their Anderson, South Carolina, apartment in August. On Thursday, investigators found Brown restrained in a metal container in Spartanburg, South Carolina, approximately an hour from her home. She told police she witnessed Kohlhepp shoot and kill Carver, and that up to four bodies might have been buried on the overgrown 100-acre lot. But Kohlhepp could be linked to as many as seven killings, authorities say.

Kohlhepp, 45, confessed to slaying seven people, including four in a 13-year-old South Carolina cold case, police said Saturday. The Superbike Killings, as the cold case became known, claimed the lives of four employees in a Spartanburg motorcycle shop. Two were shot and killed in broad daylight outside the shop. Another was shot in the back while apparently servicing a motorcycle, and a third appeared to have been ambushed as she left a bathroom. The whole incident took seven minutes or less, said a friend of the victims who discovered their bodies shortly after speaking on the phone with one of them.

The slayings appeared to lack both suspect and motive. A briefcase with money and a signed deposit slip were left untouched. Until this weekend’s discovery on Kohlhepp’s property, the shooting was “the most gruesome scene Spartanburg authorities have ever experienced,” a February 2016 cold-case report recalled.

Kohlhepp was never reported as being eyed in the killing. But he had a violent record, and was a registered sex offender, records show. He served 15 years in jail on kidnapping charges, after pleading guilty to the brutal rape of a 14-year-old neighbor when he was 15. Threatening her with his father’s gun, Kohlhepp ordered the girl into his house, where he tied her up and raped her, court records obtained by the GreenvilleOnline show.

Testimony from this 1986 case painted the adolescent Kohlhepp as a repeat offender with a lust for violence.

He promised to murder his mother in order to move in with his divorced father, prosecutors testified in the 1986 case. Upset that he received a goldfish instead of a gerbil, the young Kohlhepp allegedly poured bleach into his goldfish’s bowl; he shot a dog with a BB gun; he smashed a newly remodeled bedroom with a hammer, and destroyed other people’s belongings on a regular basis. He allegedly locked a young boy in a dog crate, rolling the cage over and over until the child was crying and the young Kohlhepp was laughing.

He was kicked out of Boy Scouts for behavioral issues and struggled in school, eventually attending a mental-health clinic in 1980 at the age of 9 or 10. Progress reports from the clinic described Kohlhepp as antisocial, self-centered, and obsessed with sex, prosecutors testified.

Anger was the only emotion Kohlhepp was capable of showing, his father told a probation officer.

Authorities feared Kohlhepp’s behavior would only worsen after he completed 15 years in jail, a reduced sentence reached as a result of his plea bargain.

“It would appear that his behavior has been progressively worsening and now, it has escalated to the point where he has sexually assaulted an innocent child,” probation officer Kim Otto testified in a pre-sentencing report. “One can only speculate as to where the defendant’s behavior will lead. It is this writer’s opinion that it is this type of individual, one with little or no conscience, who presents the greatest risk to the community.”

The report was darkly prescient. Like Kohlhepp’s childhood victim, Kala Brown and Charlie Carver might also have been kidnapped at gunpoint. Brown sometimes worked cleaning properties for Kohlhepp, who ran a real-estate business. When Brown and Carver disappeared Aug. 31, they had driven to a rural lot Kohlhepp owned, under the assumption that they would help clean the property, one of Brown’s friends reported.

“They were going to do some work, help cleaning up the property. And he pulled out a gun and took them hostage,” Brown’s friend Daniel Herren told the Associated Press.

Herren said Kohlhepp fed Brown once a day, likely fast food. A vast stockpile of guns and ammunition were found on Kohlhepp’s property. “It’s unbelievable how much he had,” prosecutor Barry Barnette testified Friday.

The investigation into Brown and Carver’s disappearance spanned multiple jurisdictions, but did not appear to focus on Kohlhepp until recently.

Anderson Police Chief Jim Stewart, whose jurisdiction launched the investigation, told the Associated Press that authorities searched the rural property, because it was the last place a cellphone related to their search had pinged.

The whereabouts of the couple’s cellphones, particularly Carver’s, have been central to the missing person’s case. After the pair disappeared, Carver’s Facebook account continued to post chilling updates, claiming he and Brown were married and expecting a baby, to the distress of friends and family who suspected an impostor.

“Im just missing to everyone else,” Carver’s account told a friend in a series of September messages shared with The Daily Beast. “We [are] both ok. there is only one person that knows where we are … the person that means the most to me and kala she know where we are and we are coming that way for ever.”

The person declined the friend’s pleas to video chat.

Facebook can track a user’s location, provided they have their location settings turned on. If served with a subpoena or a search warrant, Facebook will share this information with law enforcement. But as of Oct. 12, over a month after the couple’s disappearance, Anderson police had not served Facebook with a warrant, a spokesperson told The Daily Beast in October.

“To do anything like that, we’d have to issue a search warrant to Facebook,” Lt. David Creamer of the Anderson Police Department said. “I don’t know if we’ve done that but I’m pretty sure we have not done that… You’d have to serve [Facebook] with a search warrant to search their records for an IP.”

Information on the investigation that led to Brown’s discovery on Kohlhepp’s property is still emerging.

“Basically through our investigation, he became a person of interest,” an Anderson Police spokesperson told The Daily Beast on Friday. “They did research and found that he was a registered sex offender.”

Kohlhepp was charged with kidnapping on Friday, and with four counts of murder on Sunday. He has not yet been charged with Carver’s murder. The two other people he allegedly confessed to killing remain unnamed.