One serial killer, serving life in prison for his crimes, has urged Long Island serial killer suspect Rex Heuermann to tell the truth and plead guilty to the crimes he’s accused of committing.

In an interview with Florida officials who last week identified one of his victims, Keith Jesperson, the 68-year-old inmate known as the “Happy Face Killer,” says he frequently tells other serial killers to come clean.

“I recently got a letter from Rex Heuermann from the Long Island serial killer, and I told him the same thing,” Jesperson says.

“And he wrote me back and said, ‘I’ll take it under advisement,'” he adds, rolling his eyes and chuckling.

Jesperson, a long haul trucker, got the moniker “Happy Face Killer” from the smiley faces he drew on letters sent to media and investigators describing his crimes.

Okaloosa County officials last week charged him with the murder of Suzanne L. Kjellenburg, 34, whose body was found in a wooded area off Interstate 10 near Holt, Florida, but not identified until recently. In September, Okaloosa investigators travelled to the Oregon State Penitentiary in Salem, where he is serving his time, to speak with him about Kjellenburg.

Jesperson previously admitted in 1996 to killing a woman two years earlier whose name, he thought, was Susan or Suzette. In the September interview, he described meeting her at a rest stop, where she told him she wanted a ride to Lake Tahoe. He told her he didn’t know where he was going yet, but that he’d be heading for Washington and could get her near Tahoe.

The trucker told the investigators that at a stop at a Florida rest area, Kjellenberg started screaming.

“She just sat up and started screaming,” Jesperson said. “I was like, ‘Shut up!’ and the more I told her to ‘shut up,’ the more she screamed.”

“And I don’t need that,” he said,”because I wasn’t supposed to have people in my truck anyway … so I just killed her.”

“It was an easy thing to do,” he said, after having already killed so many people.

Jesperson has claimed to have killed more than 180 people, but authorities have only confirmed eight.

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[Featured image: Suzanne Kjellenburg and Keith Jesperson/Okaloosa County Sheriff’s Office]