Corrections officials say two inmates murdered a third inmate at High Desert State Prison near Susanville. Saturday evening inmates were in an exercise yard when guards say they saw Pedro Ayon and Brandon Martinez attacking Jeffrey Concepcion. The fight was broken up and Concepcion was taken to the prison infirmary, where he died. An investigation is underway. The 43-year-old dead man had been serving a life sentence without the possibility of parole for a first degree murder he committed in Monterey County. Ayon was serving 27 years for second degree murder, assault and attempted carjacking in Tulare County. Martinez, a Yuba County man, was serving 18 years for felony assault and robbery.