An undocumented immigrant who pleaded guilty to murdering a teenage couple in north Alabama 13 years ago has died in prison.

Felix Ortega, 39, who was serving two 15-year-sentences for murder in connection with the 2009 car crash that killed two Huntsville teenagers — 16-year-old Grissom High School sophomore Leigh Anna Jimmerson, and her boyfriend, Tad Mattle, 19, a 2008 Grissom graduate –, died Tuesday, the Alabama Department of Corrections told WHNT.

Ortega, who was serving his sentence at Elmore Correctional Facility near Montgomery, was found unresponsive in the prison’s common area, the agency said.

Life-saving measures were taken before Ortega was transported to a local hospital, where he died.

ADOC is investigating his death.

Prosecutors said Ortega had a blood alcohol level more than three times the legal limit at the time of the April 17, 2009, crash, which took place at the intersection of Airport Road and Whitesburg Drive in Huntsville.

Ortega pleaded guilty to murder in connection with the incident in 2010.