A judge in Amarillo accepted a plea agreement Wednesday from 29-year-old Wilbert Ramon Banks.
Banks had faced a possible death penalty if convicted of capital murder in the 2009 double slaying. Investigators say Banks shot 24-year-olds Stephanie Beard and Daniel Brittain because he was enraged that the pair helped his girlfriend.
Police say Beard pointed the gun at his girlfriend and tried to shoot her, but the weapon jammed.
Banks was sentenced to life in prison without parole for capital murder and 10 years in prison for assault with a deadly weapon.
