While the world focused its attention on the mass shooting in San Bernardino, a psychiatrist testifying in a northern California courtroom described the deranged thinking of a man believed responsible for another mass homicide.

One Goh bought a gun he used to kill seven people at Oikos University in 2012 to try to “spook” the Oakland school’s administrators, who he believed planted a tracking device in his car and cameras in his home, Dr Jessica Ferranti testified this week.

Goh, 47, suffers from paranoid schizophrenia and is incompetent to stand trial for the killings at the tiny Christian college where he once studied nursing, she said. A University of California at Davis forensic psychiatry professor, Ferranti spent two days on the witness stand and was the first of five experts scheduled to testify about Goh’s fitness for trial in Alameda County superior court in Oakland this month.

The hearing offers a rare view into the psyche of an alleged mass shooter who lived to tell his story.

Wearing a red jail suit and flip-flops, Goh addressed the court only once at the beginning of the proceeding. When Judge Gloria Rhynes asked if One L Goh was his true and correct name, he looked at her, nodded, replied “yes”, then stared down through his black glasses at his hands shackled in his lap.

The husband, the daughter and the fiancé of two women slain at Oikos struggled to find a comfortable posture in wooden courtroom chairs. They listened to Ferranti’s testimony in anguish, longing for justice and closure more than three years after their loved ones were shot to death in a nursing school classroom where they had studied with the man accused of killing them.

As Ferranti testified, American politicians debated gun control and discussed overhauling the nation’s approach to mental illness as a possible shield against the death toll from almost daily mass shootings. Before Judge Rhynes called for the lunch recess on the first day of the hearing, shots rang out and killed 14 people in San Bernardino, California.

The Oikos tragedy made the record books on 2 April 2012 as the deadliest outburst of violence at an American college since 2007, when a Virginia Tech University student killed 32 and wounded 25. Last month, a shooter in southern Oregon pushed Oikos down a notch on the macabre list when he killed nine at Umpqua community college.

The Oregon rampage ended like many – the gunman killed himself. The massacre in San Bernardino concluded like others frequently end – with police killing the suspects.

Goh considered suicide, he told Ferranti. He would nevertheless welcome the death penalty, she testified.

“He expressed to me that he was too much of a coward to kill himself, for someone else to do it would be wonderful,” Ferranti said.

But he does not want to plead guilty, does not believe he is guilty of seven murders and three attempted murders as charged, and first wants to make a statement to the families of the seven victims. He wants to tell them that he did not mean to kill his former classmates and instead intended to kill faculty.

Goh turned himself in and confessed to police within hours of the massacre. But in 2013, after two psychiatrists found him incompetent to stand trial, a judge suspended criminal proceedings against him.

Since then, he has been housed at Napa state hospital, a psychiatric facility, where he has been forcibly medicated. In July, psychologist Todd Schirmer found Goh competent to stand trial. Schirmer is scheduled to testify on Wednesday.

The prosecution believes that Goh is now fit to stand trial on charges that could lead to a death sentence. The Alameda County district attorney has not yet decided whether to seek capital punishment.

Ferranti deems Goh incompetent to stand trial because she believes he is incapable of assisting his attorney in his defense. She described him as plagued with delusions, auditory and visual hallucinations and undiagnosed schizophrenia stretching back for more than a decade.

Goh moved into his car after coming to believe that Oikos staff had installed surveillance cameras in his home, Ferranti said. He then abandoned his car after becoming convinced that school staff planted a GPS device inside it, she said.

“He was so certain that he was being followed that he went into a gun store to spook them,” she said.

Goh admits going to Oikos armed with a .45-caliber handgun and four fully loaded magazines the day of the shooting looking for a school administrator who refused to refund his tuition after he failed a class. But the administrator was not there.

Ferranti examined Goh twice, once in 2012 and again in September. Altogether, she spent about six and a half hours with him. She said Goh denies that he is mentally ill.

Goh’s attorney showed the court video clips of Goh in police custody just hours following the morning massacre. One clip shows the short and stout Goh alone in a small interrogation room standing next to a table and agitatedly talking to himself in his native Korean. In another, Goh sits and repeatedly writes with his finger on an empty, white table.

Judge Rhynes is expected to rule on Goh’s competency following the hearing, which continues until at least 15 December.