The Hernando County Sheriff's Office announced it identified one of two sets of unidentified remains left in the Mansfield serial killer investigation from 1981.
Through extensive work with DNA samples, investigators were able to identify them as 18-year-old Theresa Fillingim. The teen was reported missing by her sister, Margaret Johns, to the Tampa Police Department back on May 16, 1980, the agency said in a statement.
Her remains were found on the property of William "Billy" Mansfield's family on April 3, 1981.
Back in the spring of 1981, four sets of human remains were recovered from the Manfield property in Hernando County. KIRO-TV reports authorities were able to arrest the then 25-year-old electrician for the murders of five woman, including a 15-year-old girl.
Mansfield is now serving concurrent life sentences handed down from both Florida and California, where we killed 29-year-old Rene Saling on Dec. 6, 1980, the media outlet explains.
The other people identified by police as lives lost at the hands of Mansfield are 21-year-old Sandra Graham and 15-year-old Elaine Ziegler.
The two other remains unearthed on the family's property were left unintended — until now.
Investigators with the sheriff's office in 2020 reached out to the University of North Texas and Parabon Nano Labs for help in the investigation, submitting DNA in hopes of finding answers. After continuous trial and error, finally, the complete DNA profile was reviewed and it was determined that a sufficient sample of the unidentified person could be used for further testing.
Using the company's Snapshot DNA Phenotyping Service, trait predictions of the person's ancestry, eye color, hair color, skin color, freckling and face shape were made, the sheriff's office said in a statement.
With all of this information now available, investigators were able to follow up on the lead and identify Fillingim.
With the success of the technology and techniques used, the sheriff's office says it will continue to use it to help solve violent crimes.