LAS VEGAS >> Authorities were searching Tuesday for a 42-year-old convicted bombmaker who escaped from a Nevada prison where he was serving a life sentence for a deadly 2007 explosion outside a Las Vegas Strip resort.

Gov. Steve Sisolak ordered an investigation into the incident after he said late Tuesday his office learned the escapee had been missing from the medium-security prison since early in the weekend.

“This is unacceptable,” Sisolak said in a statement.

Officials didn’t realize until Tuesday morning Porfirio Duarte-Herrera was missing during a head count at Southern Desert Correctional Center near Las Vegas. A state Department of Corrections statement said search teams were looking for him.

Duarte-Herrera, from Nicaragua, was convicted in 2010 of killing a hot dog stand vendor using a motion-activated bomb in a coffee cup atop a car parked at the Luxor hotel-casino.

Records show his co-defendant, Omar Rueda-Denvers, remained in custody Tuesday. The 47-year-old from Guatemala is serving a life sentence at a different Nevada prison for murder, attempted murder, explosives and other charges.

A Clark County District Court jury spared both men from the death penalty in the slaying of Willebaldo Dorantes Antonio, whom prosecutors identified as the boyfriend of Rueda-Denvers’ ex-girlfriend.

Prosecutors said jealousy was the motive for the attack on the top deck of a two-story parking structure. The blast initially raised fears of a terrorist attack on the Strip.

Officials described Duarte-Herrera as 5 feet, 4 inches tall and 135 pounds, with brown eyes and brown hair.

Sisolak said his office ordered corrections officials to “conduct and complete a thorough investigation into this event as quickly as possible.”

“This kind of security lapse cannot be permitted and those responsible will be held responsible,” he said.