What happened to Theresa Fillingim? Case explored as remains of missing teen is found at killer’s home after more than 40 years

After 40 years, a Florida woman said her family has finally found closure after learning that the remains of her sister, Theresa Fillingim, were found. Fillingim vanished in the Tampa region in 1980, and the remains were discovered recently at a Spring Hill home that formerly belonged to a serial killer.

The Hernando County Sheriff's Office got in touch with Margaret Johns, Theresa's sister, last year regarding Theresa Caroline Fillingim, who vanished in 1980 in the Tampa, Florida, region when she was 17 years old.

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Theresa Fillingim's sister allegedly has answers about what happened to her

Johns told the sources that when she was called, police met with her to collect a DNA sample in order to create a timeline. In July 2021, six weeks after the police first contacted her, she discovered that the DNA sample had been a hit.

She said,

It gives me peace because I know I didn't lose her. She was taken."

The Hernando County Sheriff's Office claimed in a statement shared on Facebook on Wednesday that Theresa Fillingim's remains "identified one of the two remaining unidentified victims in the Mansfield investigation from 1981."

Reports suggest that Billy Mansfield Jr., a convicted serial killer, was given a life term in prison after being found guilty of the 1982 killings of five women in Florida and California.

The statement explained,

"In March and April of 1981, four sets of human remains were recovered from the Mansfield property located in Hernando County. Two of the victims were immediately identified. The other two victims remained unidentified until now, where one of the victims has recently been positively identified."

The investigation was going in vain even though the remains were gathered in 1981 and transported to multiple labs to be verified.

The sheriff's office reported that a sample of the remains was sent to the University of North Texas in 2020. Officials were able to create a comprehensive DNA profile, which was entered into a national database. However, searching that database was futile, but hope was not lost.

The statement continued,

"However, the complete DNA profile was reviewed, and it was determined that a sufficient DNA sample of the unidentified victim existed for further testing."

The authorities also sought assistance from Virginia-based Parabon Nano Labs, a DNA technology business, and the University of North Texas. The company's Snapshot DNA Phenotyping Service was then used by law enforcement to generate "trait predictions for the associated victim."

The statement added,

"Individual predictions were made for the victim's ancestry, eye color, hair color, skin color, freckling, and face shape. Parabon's research developed a profile that was utilized in the identification of the victim in this case."

The statement said that from there, detectives could establish that Theresa Fillingim was one of the unnamed victims.

According to Johns, who spoke to WFLA, her brother will divide the ashes of Theresa Fillingim after her body is cremated.