Mendez was convicted of first-degree murder and second-degree robbery. A jury found him guilty of luring and ambushing Jamie Sharif Mohammad Abuawad, 27, a gold buyer, a block from his residence in April 2012.
Abuawad was shot three times with .380-caliber revolver, according to the L.A. County District Attorney's Office, after Mendez called him four times that day, the last call coming shortly before the murder. Mendez made off with $300 and two cellphones.
Last Wednesday, Mendez, a gang member, was escorted unrestrained into the courtroom in civilian clothes. He picked up a chair and threw it at an LAPD detective and an L.A. County deputy district attorney.
The detective was hospitalized with an injury to the back of her head and shoulder area, and was listed in good condition. The deputy district attorney was hit in the upper torso and was treated at the scene for minor injuries, according to the L.A. County Sheriff's Department.
The defendant was subdued by the bailiff and other officers. The jury was not present when the chair-throwing incident occurred, but family members of the victim in the murder case were in the courtroom and witnessed the attack. Mendez had not previously displayed hostility in court.
Mendez is scheduled to be sentenced on February 11. He faces up to life in prison without possibility of parole, the D.A.'s office said.
Jurors spent less than three hours deliberating.