Des Moines police say a man, originally wanted as a material witness in a weekend stabbing death, is now charged with first-degree murder. Authorities caught up with 19-year-old Luis Alvarado on Wednesday near Frisco, Colorado.

They traced Alvarado’s cell phone after he called 9-1-1 claiming he was being held hostage on a bus. The Colorado State Patrol evacuated the bus, but did not find any evidence that Alvarado was being held against his will.

Des Moines police believe Alvarado is responsible for killing 16-year-old Eduardo Marquez at a house party last weekend in Des Moines. Marquez, who was a star soccer player at Des Moines East High School, was dropped off outside Broadlawns Medical Center late Saturday night with a stab wound. He later died from his injuries.