Long-haul trucker Keith Hunter Jesperson killed at least eight women across the United States in the 1990s and sent authorities confession letters signed with smiley faces. But the identity of his last known victim remained a mystery for three decades.
Florida authorities this week identified her as Suzanne Kjellenberg, who was 34 when she was killed in Jesperson's cross-country murder rampage.
Landscapers found her remains along Interstate 10 in September 1994, said Sheriff Eric Aden of Okaloosa County in Florida.
Jesperson, dubbed the "Happy Face Killer" for his letters, had confessed to killing a woman named "Susan" or "Suzette" after his arrest at the time, but her identity was unknown for decades, Aden said.
Of the eight women he admitted to killing, she was the only unidentified person until now, the Okaloosa County Sheriff's Office told CNN.
Serial killer detailed victim's last moments
Jesperson got the nickname "Happy Face Killer" after he sent confessions to journalists and police departments around the country to gain notoriety.
His victims spanned six states: California, Nebraska, Wyoming, Oregon, Washington and Florida. He was arrested in the mid-1990s and is serving seven life sentences at the Oregon State Penitentiary, Aden said.
In a recent prison interview, he told investigators how he met Kjellenberg at a truck stop near Tampa and they traveled together to a rest area. He parked next to a security guard and approached the victim as she slept in the truck's bed, Aden said in a news conference earlier this week.
He told investigators she began screaming and wouldn't stop. He was not allowed to have unauthorized riders in his truck, and didn't want to draw the security guard's attention, so he put his fist against her neck and placed zip ties around her throat, Aden said.
Investigators visited the killer at the prison last month on the anniversary of the day her body was found 29 years ago and coaxed him into a confession, Aden said.
"This interview was unannounced. He did not know they were coming, but he fully cooperated. He talked openly about the murder and how it took place," Aden said. "He dumped her body a short time later in Holt on the side of the I-10."
Investigators have tried to identify her for years
For years, investigators worked to find the identity of the final victim's skeletal remains. At the time of her death, Kjellenberg was a drifter and had no known job, Aden said.
In 2007, a forensic artist completed a facial reconstruction to help identify her, but it did not generate any leads, the Okaloosa County Sheriff's Office said. A year later, it sent the remains for additional anthropological examination. It also sent specimens to the FBI lab for DNA analysis and entry into the National Missing and Unidentified Persons System database.
A break in the case came when the medical examiner's office sent samples to Othram, a Texas-based company specializing in forensic genetic genealogy. It created a genealogical profile to assist in the victim's identification.
"From the analysis, they were able to narrow down a family member and a family member gave a sample and it became a 100% DNA hit," Aden said during the news conference.
The forensic sequencing laboratory has provided several law enforcement agencies with advanced DNA testing and forensic-grade genome sequencing, leading to major clues in cold cases.
"Suzanne deserves a voice, and we're that voice for her today," Aden said. He said her family lives in Wisconsin and has requested privacy.
"Thanks to the tireless efforts of so many over so long, the remains of Suzanne Kjellenberg, the final unidentified victim of Jesperson's cross-country murder sprees, can finally leave the medical examiner's office, and return home," Aden said.
Jesperson has been charged with one count of homicide in Florida.