Criminalist testifies on DNA evidence in Mollie Tibbetts trial

May 22 (UPI) -- Blood found in the trunk of Cristhian Bahena Rivera's car was a match for that of Mollie Tibbetts, the University of Iowa who was abducted and killed in 2018, a DNA analyst testified Friday.

Bahena Rivera, 26, is currently on trial for first-degree murder in the death of 20-year-old Tibbetts, who disappeared while running in July 2018 in Brooklyn, Iowa.

Investigators found her body a month later and determined the cause of death was "homicide resulting from multiple sharp force injuries."

Tara Scott, a criminalist in the DNA section of Iowa's crime lab, told jurors Friday she analyzed a swab taken from a blood stain found in Bahena Rivera's Chevy Malibu and it matched the profile of Tibbetts' blood.

She also said many of the stains found in the trunk of the suspect's car contained DNA from multiple people, were too weak and contaminated to conclusively include or exclude anyone as a match -- and that DNA evidence can be degraded by a number of factors, which could have affected Tibbetts' body.

In 2018 Bahena Rivera told police to approaching Tibbetts while she was running, but doesn't remember what happened after that, and entered a not guilty plea after he was charged.

Defense lawyers argued Friday that his partial confession was false and coerced as a result of sleep deprivation and harsh questioning techniques, and played videos in court showing Bahena Rivera sleeping during the 11-hour interrogation.