Todd Kohlhepp may have pleaded guilty to seven murders, but that might not be the extent of his crimes, experts say.

Criminal profilers and family members believe the South Carolina serial killer, who was sentenced to life in prison Friday, likely is responsible for additional unsolved homicides.

Spartanburg County Sheriff Chuck Wright said investigators are going back through old cases to "make sure we hadn't missed anything" that might connect to Kohlhepp, a 46-year-old former real estate agent, amateur pilot and registered sex offender.

“We have some unsolved cases in Spartanburg County I’d like to solve," Wright said. "All of them are solvable, we just have to have the right tip like we did with this one.”

Experts who have been following the case think it's probable more crimes will be uncovered.

“I absolutely, positively believe there are other victims out there. These guys never give it all up. They always come back for various reasons,” said John Kelly, a serial killer profiler with S.T.A.L.K. Inc., based in New Jersey. Kelly has 20 years of experience profiling serial killers.

He said it's rare to find someone like Kohlhepp who is both a mass murderer and a serial killer.

Kohlhepp confessed to killing four people at Superbike Motorsports in Chesnee in 2003. He also killed a Spartanburg couple, Johnny and Meagan Coxie, in December 2015 and an Anderson man, Charlie David Carver, in November 2016.

“There’s more here. … I don’t think you’ve heard the last of him,” Kelly said.

As a teenager, Kohlhepp was accused of sexually assaulting a 14-year-old girl at gunpoint, and spent 15 years in an Arizona state prison after being convicted of kidnapping in the case. The sexual assault charge was dropped as part of a plea deal that required Kohlhepp to register as a sex offender.

Kelly said he would be surprised if Kohlhepp hadn't committed other sex offenses between the time he was released from prison and his arrest following the discovery of kidnapping victim Kala Brown, who was sexually assaulted while being held prisoner by Kohlhepp.

"He's a sexual sadist," Kelly said.

He said Kohlhepp could take his time before he decides to “throw some bait out there” to law enforcement that uncovers a new case.

Kelly also said Kohlhepp’s guilty plea was most likely an act of control to avoid the death penalty than a demonstration of remorse.

“These guys have no empathy. … They do not have the capacity, whether it's a mixture of genetics or a rough childhood environment,” Kelly said. “It’s a them against society kind of mentality.”

Family members of Kohlhepp's victims echoed Kelly's assessment.

“He showed no remorse. I mean nothing,” Chuck Carver, the father of Charlie David Carver, said of Kohlhepp's appearance at the plea hearing. “It was just like a body standing up there with no soul.”

Enzo Yaksic, co-director of the Atypical Homicide Research Group at Northeastern University in Massachusetts, said his assessment is somewhat different.

Using words like "remorseless," he said, "removes the need for us to consider serial murderers to be human beings that process their environment in much the same way as we all do. Kohlhepp may present as alternate halves of the same whole — a vengeful murderer operating at the behest of his own rage, and a confused yet remorseful individual that confessed his crimes to his mother.”

Authorities said Kohlhepp asked to meet with his mother after he was arrested so he could tell her himself about the murders.

Yaksic said the public may not hear much more from Kohlhepp. He expects Kohlhepp eventually will provide a statement apologizing for his crimes.

“I imagine that his remaining days will be spent introspecting, examining his own actions not to relive and revel in them for the selfish purposes of gratification, but to honestly comprehend them within the scope of what it means to be labeled as a serial homicide offender,” Yaksic said.

Terry Guy, the widower of Superbike Motorsports victim Beverly Guy, said he believes the investigation could widen, since Kohlhepp was an amateur pilot.

“I honestly do not believe he went from 2003 to 2015 without killing anybody. He owned his own plane and a helicopter. He could go anywhere,” Guy said.

Tom Lucas, the father of Brian Lucas, another of the Superbike victims, made two pleas in his statement Friday at Kohlhepp's hearing. One was for Kohlhepp to come forward with any information about other victims. The other was for local law enforcement to look into unsolved cases in Spartanburg County.

“Please come clean. Bring out those other victims. .. If there's more, get it out," Lucas said.

Wright said he’s committed to helping close any cases that might be tied to Kohlhepp.

“We owe it to the families to do that,” Wright said.

He declined to say whether Kohlhepp might be charged in additional cases.

“You’ll understand later. We’ll have a different conversation later,” Wright said.

Shane Gorenson, Kohlhepp’s attorney, said during the hearing there are no other victims.

“Mr. Kohlhepp has come clean,” Gorenson said. “We hope (the families) will be able to find peace starting today.”

But Lorraine Lucas, Brian Lucas's mother, said she doesn't believe Gorenson.

“His attorney says, ‘Oh, there are no others.’ Yeah, right,” she said.

Kelly said Kohlhepp could decide to offer new tips later on as a way to get attention.

“I think he’s going to have a hard time not being in the limelight,” Kelly said.