and she also sought help from an expert on wrongful convictions, martin yant.her, they pored over the case file and discovered some important pieces of information. first, the witness who testified clarence elkins threatened judy johnson's life during a telephone call also claimed judy called 911 to report the threat to police. but there was no evidence judy johnson ever called 911. >> the 911 call should have been logged. it was obvious no such phone call had been made. >> and they also discovered that the coroner took vaginal swabs from judy johnson during in the autopsy. on those swabs, lab tests found a substance called acid phosphatase, an enzyme found in the male prostate gland. but those swabs were never tested for dna. >> to be fair, technology in forensic science is constantly improving. >> six years after the murder, melinda elkins received permission from the court to test the swab taken from her mother's autopsy. the forensic lab was able to identify a dna profile from that swab. as melinda always claimed, the dna did not belong to clarence elkins.