CLOVIS, N.M.—Five inmates who broke out of a New Mexico jail—including a killer and a man accused of murder—remained on the loose Tuesday, and a prosecutor said investigators were focusing on the possibility that someone inside aided in the weekend escape.

Eight inmates escaped Sunday from the Curry County jail, but one was quickly captured and two others were caught in nearby Texas. District Attorney Matt Chandler said investigators believe some of the remaining escapees could be in west Texas.

“We’re still receiving tips that some of the other fugitives, at least one or two of the other fugitives, could be in” the Lubbock area, he said.

Chandler told The Associated Press in a phone interview that New Mexico State Police began looking closely Tuesday at whether anyone inside the jail helped the men escape.

They are “working that angle very hard, and that’s going to be a very high-priority focus,” he said. Chandler did not say what led investigators to suspect that the inmates might have had inside help.

The eight men were discovered missing late Sunday when Clovis police officers noticed two people in orange jumpsuits running near the jail, according to Curry County Sheriff Matt Murray. Authorities believe the men used handmade instruments to cut a hole in the roof near a skylight.

Among the escapees are convicted murderer Edward Salas, 23, of Clovis, and 19-year-old Larry McClendon, who was being held on an open count of murder and aggravated robbery.

Salas was sentenced to life in prison last month for the 2005 shooting of a 10-year-old Clovis boy; the child was killed when shots were fired through his bedroom window as he slept. Salas was being held at the jail before being transferred to the state Department of Corrections.

McClendon, of Plainview, Texas, was charged with an open count of murder in March for his role in the January 2007 slaying of a secondhand store owner in Clovis.