Utah kidnapper is woman's father after switching his sperm at Salt Lake City clinic

A convicted Utah man who was jailed for abducting a female student secretly fathered a child after allegedly swapping a sperm sample with his own at a fertility clinic where he was previously employed.

The family, who chose to remain anonymous claim they discovered their daughter, 21, was in fact the child of kidnapper Thomas Lippert, who worked at the same Salt Lake City area facility the couple used to conceive their child.

The discovery was only made when the family began researching their lineage with a genealogist, who informed them that their daughter and her father did not share the same DNA.

"I felt my stomach just drop," the mother told the station. "When I called my daughter and my husband's DNA up next to one another they didn't share any DNA at all, and I just thought to myself, 'oh my God."

Using the genealogy results, the mother then managed to trace a cousin of Lippert, and a further DNA tests on Lippert's mother confirmed he was the biological father.

Lippert, who died in 1999, reportedly served two years in prison for kidnapping a college co-ed in 1975. Lippert allegedly used electric-shock treatment on his victim, CBS news have reported.

There are no remaining records from the clinic to prove the family's claim however, or to find evidence of other children Lippert may have fathered.

Lippert's widow told the Salt Lake Tribune: "I think, because Tom didn’t have any kids, he wanted to have a lot of kids out there. He claimed to be a frequent sperm donor and maybe he switched some samples so he could have more of his kids in the world."

The now defunct clinic was associated with but not owned by the University of Utah, who are now offering free paternity tests to parents who may have used the clinic between 1988 an 1993.

"Since April 2013, the University of Utah has been investigating credible information regarding the possible mislabeling or tampering of a semen sample," the university said in a statement.

"Through genetic testing, a woman who received artificial insemination (AI) in 1991 discovered the biological father of her child was not her husband, as she had assumed. She traced the genetics of her child to a man who was a former employee of a now-defunct medical lab, Reproductive Medical Technologies Inc., (RMTI). The man in question was also a part-time employee of the University from 1988-93. The woman recalls that her husband’s semen preparation was prepared by RMTI.

"There are no remaining records from RMTI to prove the claim and the man in question has been deceased since 1999. Consequently, it is unknown how this incident might have happened. In addition, there is no evidence to indicate this situation extends beyond the case in question."