James Martin

The DNA from a 14-year-old Bronx girl’s unsolved murder case helped bring her killer to justice after 18 years.

James David Martin, who is in his 40s, pleaded guilty Thursday to the 1998 murder and rape of Marleny Cruz.

Martin pleaded guilty to first-degree manslaughter in Bronx Supreme Court, and will be sentenced to 20 years in prison, the NY Daily News reports.

The suspected serial rapist and killer is already serving between 22-44 years in a Pennsylvania prison for strangling his wife to death when she threatened to leave him in 2005.

NY Daily News — Police found Cruz’s partially clothed body dumped on Valentine Ave. in University Heights on Feb. 23, 1998. She had been sexually assaulted and strangled.

Her death was a cold case until the Bronx Homicide Squad and the district attorney’s office discovered Martin’s DNA underneath Cruz’s fingernails – using new technology to re-test the evidence.

At age 17, Martin killed a high school classmate for his coveted Air Jordan sneakers. The murder made the May 14, 1990 cover of Sports Illustrated.

James Martin