Scotty Blair, 41, faces several felony counts including assault and burglary.
The physical evidence is ever present on this man's right hand. The tip of his finger was bitten off by Blair last May.
The victim testified Tuesday afternoon, Blair broke through the front window of his Northwest Fresno home then bit him as he tried to get Blair out of his house.
"Grabbing my fist he pulled my right hand up to his mouth and he sunk his teeth into the middle finger of my right hand."
Neighbors living near north Manor Avenue called 911 on May third -- when they say Blair was terrorizing them around 5:45 that morning. They say he banged on their doors and windows. One witness says Blair was grunting and growling at him.
"I saw the defendant was standing there at the door and literally almost hammering his fists against the security screen door. The best I can describe was his eyes were as big as saucers. And he was sort of making a half gasping half hyperventilating sound."
Investigators say Blair was tearing apart yards in the area -- biting fences and yelling. In court, a Fresno police officer said Blair was incoherent. His attorney tells ABC30 -- Balir was high on drugs -- but there's more to what happened.
"Yes, there's a toxicology report that says he tested positive for methamphetamine," said Defense attorney Robert Dulce. "That's one factor, the other factor here is the mental defect we're talking about."
He says his client has no criminal history, but he has a long history of mental illness. Which he intends to prove when the case goes to trial.
Blair will be in court in October. His attorney is hoping to get him mental health care and substance abuse treatment.
