This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

A typo in the original story has been corrected.

OKLAHOMA CITY (KFOR) – The death penalty trial for accused serial killer William Lewis Reece in the 1997 murder of Tiffany Johnston continued Friday afternoon in the Oklahoma County Courthouse.

On day four of the trial, jurors got a crash course on DNA testing and heard from two DNA analysts and the Texas Ranger who obtained the sample from Reece.

The 19-year-old vanished from the Sunshine Car Wash in Bethany. Her white dodge neon was still in the cleaning stall and her matts were still hanging up on the wall.

The next day, her body was found naked in a Canadian County field.

The medical examiner previously told the jury she took vaginal and rectal swabs before sealing it into evidence.

Attorneys on both sides and witnesses pointed out DNA technology was just beginning in 1997 and wasn’t as reliable to point out a suspect.

After an exhaustive search for possible suspects, the Johnston’s murder case went cold and critical DNA puzzle pieces faded away.

The scientists who processed the 13-year-old DNA when the case was reopened in 2013 took the witness stand Friday. She told the jury she could only pull some information from the samples to make a partial profile.

A former Texas Ranger also testified Friday. He told the jury at the time Reece was already on the Oklahoma State Bureau of Investigation’s radar. The bureau reached out to him asking if he could obtain a buccal swab from Reece, who was currently serving a 60-year sentence in a Texas prison for kidnapping a woman at knifepoint.

The exchange was all captured on audio tape. Jurors were able to hear Reece voluntarily giving the ranger a sample.

The Texas Ranger could also be heard telling Reece investigators already knew he had been in Oklahoma around the time of Johnston’s murder based on calling card data.

Reece can eventually be heard recalling being in the state at the time and allegedly had a relationship with Johnston’s mother, but never met or saw pictures of Johnston.

Back at the DNA testing lab, OSBI investigators compared Reece’s DNA to the unknown sample. The investigator testified all of the known puzzle pieces matched up with Reece’s direct sample. During her testimony, the investigator noticed it was not a 100% match, but Reece could not be excluded as a possible suspect.

Meanwhile, Reece is also linked to three other murders in Texas. All of the victims were around Johnston’s age and murdered around the same time.

So far, prosecutors have called around 20 witnesses in the trial.

More are expected on Monday when the trial starts back up again at 9 a.m.