DNA Proves He Raped, Killed a Girl—and Someone Else

Las Vegas police say they finally know who killed a 14-year-old girl during her walk to school more than 32 years ago. Stephanie Isaacson never arrived at school on June 1, 1989, a fact her father only learned when she failed to appear that afternoon. Her body was found that evening 25 yards off a trail through the empty sandlot she passed through on her walk. She'd been strangled and sexually assaulted. There was no DNA match to semen found on Stephanie's shirt, and the case grew cold, per the Washington Post. Then in November, genome-sequencing lab Othram reached out to police, saying local philanthropist Justin Woo had donated the funds needed to solve one cold case, per the Las Vegas Review Journal. Lt. Ray Spencer says Stephanie's case was chosen due to the small amount of DNA remaining—the equivalent of 15 human cells.

The sample "now holds the world record for the smallest amount of DNA ever used to help solve a crime," reports the Review Journal. Police announced Wednesday that they had identified the suspect as Darren Roy Marchand, who died by suicide in 1995 at age 29. He was charged with fatally strangling 24-year-old Nanette Vanderburg in her home in 1986 at the age of 20, but the case was dismissed for lack of evidence as DNA testing was not available at the time. Authorities now say DNA in the two cases matches. In a statement, Stephanie's mother says she's "glad" to finally know who killed her daughter as "I never believed the case would be solved," but "there is no justice for Stephanie at all," per KLAS. Spencer says it's unclear if Marchand knew Stephanie, but "it appears to be a random attack while she was walking to school," per the Post. (More cold cases stories.)