Farrah Fawcett and Ryan O'Neal's son violently attacked a man and left him with brutal stab wounds on his head and neck ... according to a new lawsuit.
As we reported ... Redmond O'Neal was charged with attempted murder after an alleged series of violent and random attacks last month in Los Angeles. Now, one of his alleged victims has provided details of the assault, claiming O'Neal drew a knife and plunged it "three and one-half inches into [his] brain and then slit [his] throat along the carotid artery."
The man claims he was left in a state of shock and has suffered great mental and physical pain, nervous system damage and believes his injuries will leave him with a permanent disability.
He's suing O'Neal for damages and medical expenses related to his injuries.
O'Neal is accused of seriously injuring a total of 5 people. He's facing charges of attempted murder, 2 counts of assault with a deadly weapon, brandishing a knife, battery and criminal threats.