Professor Romie John Delariman met Goh when he started studying nursing at Oikos University, a small Christian school in Oakland, Calif.
He says Goh often told a story about beating someone up who tried to mug him in San Francisco, and said when he was bored he would go to the park and pick fights.
Delariman says Goh was one of his most eager students in the nursing program but he felt disrespected by his younger classmates.
Goh was arrested Monday on suspicion of opening fire at the college in a rampage that left six students and a receptionist dead and wounded three more.
