A prosecutor in the trial of a man accused of killing three managers at a Santa Clara semiconductor company in 2008 said Thursday the defendant was resentful about being fired from his $125,000-a-year job and returned a day later to shoot the victims to death.

Jing Hua Wu, a former testing engineer for the firm SiPort, Inc., "begged for his job" back during a follow-up meeting with the three victims the afternoon of Nov. 14, 2008, and when they refused, he shot them, Deputy District Attorney Tim McInerny said.

"Revenge. That's what this murder comes down to," McInerny said in his opening statement in Santa Clara County Superior Court in San Jose this morning.

Wu, 51, has pleaded not guilty to three counts of murder with special circumstances for the deaths of SiPort CEO Sid Agrawal, 56; its vice president of operations Brian Pugh, 47; and human resources manager Marilyn Lewis, 67.

The special-circumstance allegations could make Wu eligible for the death penalty if he is convicted.

SiPort, which made HD radio chips, was bought by Intel in 2011.

Thursday in court, McInerny showed jurors graphic autopsy photos of the three victims and their bullet wounds.

He said Wu had purchased a small 9mm handgun, used it to practice at a gun range in Milpitas, and bought 100 rounds of ammunition two days before the shootings -- six of which he used to shoot the victims at close range.

Moments before the shootings occurred inside Agrawal's office, employees said they overheard Agrawal exclaim, "We don't have to do it like that," to which Wu replied, "I don't care, you're just going to send me to jail," McInerny told jurors.

McInerny said the killings were "planned, purposeful and premeditated."

In his opening statement, Wu's defense lawyer, San Francisco civil rights attorney Tony Serra, described his client as "a law-abiding man, family man prior to this horrible, horrible episode," which he said resulted from Wu's family struggles in China and mental illness.

Serra said Wu grew up in Communist China. He lived through the Great Famine period of 1958 to 1961 when many people starved, and was there for the Cultural Revolution beginning in the mid-1960s when Wu's family was denounced for its previous ties to the Nationalist China movement.

Wu was repeatedly beaten for being associated with the nationalist group and once was shoved into water and nearly drowned by political opponents, causing him to suffer from post-traumatic distress disorder, Serra said.

"His whole family would hide at home at night to escape the bullying," Serra said. "He grew up fearful, he grew up distressed. He grew up in a lifelong depression."

The defendant's mother and grandmother had histories of severe mental illness, and Wu himself has suffered from paranoid delusions, has been treated for a serious form of depression and has thoughts of suicide, Serra said.

In the years prior to the shootings, Wu had money invested real estate whose value declined steeply during the U.S. economic downturn in 2008, Serra said. He faced bankruptcy, humiliation for him and his family, and then the loss of this job, the attorney said.

Wu started to have hallucinations and considered suicide prior to the shootings, and then "blacked out" and recalls shooting Pugh but not killing Agrawal or Lewis, Serra said.

Serra said the defense plans to discuss seven diagnoses from experts about Wu's "mental diseases and defects."

The defense also will offer proof that Wu's sufferings in China and his mental health problems formed the foundation for the shootings.

"We have a good, strong case as to his mentality," Serra said. "The evidence is going to show he was very, very mentally ill."

Serra concluded by telling jurors that the defense will provide them with reasonable doubt to refute the murder charges and instead convict Wu on the lesser charge of manslaughter.