FORT LAUDERDALE, Fla. (AP) — The remains of a teenager who went missing nearly 50 years ago have been identified through advanced DNA technology, and detectives believe she may have been slain by a police officer who was also a serial killer.

Susan Poole, 15, was a high school dropout whose family reported her missing just before Christmas in 1972. She had been living between the family’s home in a trailer park near Fort Lauderdale and with a friend in a nearby apartment, Palm Beach County Sheriff’s Detective William Springer said during a news conference Thursday.

“Nobody knew where she went,” he said, noting that her clothes and pocketbook were left at the friend’s apartment.

A year and a half later, in June 1974, sheriff’s deputies were called to a remote location in Palm Beach County where human remains were found.

“She was tied up in the mangroves with wire to a tree,” Springer said. “She was skeletal remains, totally nothing left of her except bones.”

Back then, detectives didn’t have the DNA technology that is now readily available, so the case quickly turned cold, he said.

In 2015, investigators submitted DNA to a national missing persons database, which turned up nothing.

Then, in December, Othram, a Texas-based forensics lab that builds DNA profiles using genealogy, contacted the sheriff’s office and said they may be able to help solve cold cases. In March, the company provided the names of the victim’s mother and siblings. Springer said they provided a DNA sample from Poole’s mother, who was verified as a match.

Now Springer is looking for evidence that connects Poole to Gerard Schaefer, a serial killer who was fatally stabbed by a fellow inmate at the Florida State Prison in 1995. Schaffer had been a police officer in Wilton Manors, a Fort Lauderdale suburb, and was a deputy with the Martin County Sheriff’s Office at the time Poole disappeared, Springer said.

Schaefer was found guilty of murdering two other girls, ages 16 and 17, who lived near Fort Lauderdale. Their mutilated and decapitated remains were found in April 1973 in Martin County. Because of a U.S. Supreme Court ruling, Florida did not have a death penalty in the early 1970s and Schaefer was sentenced to life in prison.

Because of the similar way in which those teens were killed, Springer said he believes Schaefer could have been involved in Poole’s death. Authorities say Schaefer was implicated in up to 30 deaths.

Robert Stone, who prosecuted Schaefer, once called him, “the most sexually deviant person I had ever seen. He made Ted Bundy look like a Boy Scout.”

Investigators are hoping to speak to several friends who lived near Poole when she disappeared and could possibly fill in some blanks about her activities during that time. Springer wants to know if she frequently hitchhiked or whether she had ever confided in them about any kind of relationship with Schaeffer.

For Poole’s mother, who is in her 90s, and siblings, the news has brought some closure, Springer said.

“The family was happy to know what happened,” he said. “It’s been a long time waiting to see what happened to their sister.” ___

Associated Press writer Terry Spencer in Fort Lauderdale, Florida, contributed to this report.

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