SAN JOSE  (AP) — A Silicon Valley engineer was found guilty of first-degree murder Friday for fatally shooting three executives at a semiconductor startup the same day he was fired.

The Nov. 14, 2008, shooting at SiPort Inc. is one of the worst workplace shootings to have taken place in the high tech region south of San Francisco.

A Santa Clara County jury deliberated for a day and half before convicting Jing Hua Wu, 51.

Wu's lawyer, Tony Serra, had urged the jury to convict his client of manslaughter, which is killing in the heat of passion. During the trial, Wu had claimed he fired the first of six gunshots by accident.

Prosecutors argued that Wu had planned the killings as revenge for being terminated from his job at the Santa Clara company.

The jury rejected the defense's contention that Wu was too mentally ill to form the intent to kill when he shot CEO Sid Agrawal, office manager Marilyn Lewis and supervisor Brian Pugh.

In the trial's sanity phase, the same jury will consider whether Wu was too mentally ill when he committed the murders to be held legally responsible for the crimes.

If jurors determine he was insane, Wu would be sent to a state mental hospital until doctors found he had regained his sanity or could be treated as an outpatient, according to the San Jose Mercury News (http://bit.ly/Y0Y6vm).

If the panel finds he was not insane, Wu would be sentenced to life in prison without parole.