A 41-year-old father is dead after being detained by Pasadena police after a routine traffic stop.

Michael Martinez, 41, was detained by officers on Dec. 31, 2013, near the intersection of Preston Avenue near Sycamore Street. Martinez's friends told Local 2 that when they walked up Martinez was in handcuffs, lying on the ground and motionless. 

"I seen blood on the ground, I seen his face split open and he was barely moving," said Joshua Chapman, a friend of Martinez.

Chapman believes the officers on the scene that night got rough with Martinez and slammed his head against a curb.

"While he was on the ground they hit him," Chapman said. 

Martinez was taken to the hospital where he later died. 

It's unclear what happened to him or what caused him to need medical attention but the incident is under investigation.

A Pasadena police spokesperson told Local 2 the incident is being investigated by the Internal Affairs division and will eventually be looked at by the state's Attorney General's Office. 

The cause of Martinez's death is still under investigation by the Medical Examiner's Office.