YOKOHAMA, Japan — U.S. Navy Seaman Olatunbosun Ugbogu stepped back into Yokohama District Court on Wednesday, still angling for an insanity defense.

The former USS Cowpens sailor again confessed but pleaded not guilty on the first day of his robbery-murder trial, maintaining he was commanded by "overpowering" voices to stab and kill 61-year-old taxi driver Masaaki Takahashi in an alley in Yokosuka’s Shioiri neighborhood last spring. He’s also charged with illegal possession of a knife.

"[Ugbogu] was not able to judge his actions — right or wrong," his attorney, Yasutoshi Murakami, said during the three-hour hearing. "From a legal aspect, we insist on his insanity. We will present evidence that he suffers from schizophrenia."

Murakami argued Ugbogu suffers from mental illness and is asking the three-judge panel to grant a psychiatric evaluation. He also wants to have a mental health expert listen to testimony and possibly take the stand later.

Prosecutors argued Wednesday that Ugbogu intended to kill the man and skip out on paying a $195 cab fare.

The prosecution’s summary included crime-scene photos of the taxi and a blood-stained credit card. It also showed diagrams depicting Takahashi’s stab wounds and a picture of the alleged weapon.

"The defendant is making a false statement by saying he was ordered or directed by voices," a Japanese prosecutor told the court.

Ugbogu, 22, a Nigerian citizen, was led into the packed courtroom wearing shackles, a dark jacket and striped athletic pants. He looked far more clean-cut than he did during his first court appearance in April.

On March 19, Takahashi was found in his taxi in a quiet alley with his seat belt fastened and the motor still running. Ugbogu said voices, which he describes as "spirit friends," told him to get into the cab in Tokyo, ride it to Yokosuka and stab the man in the neck.

Ugbogu was in deserter status from his command when the alleged crime occurred. His credit card was found in the taxi.

"The girl I was living with went to work and I heard voices saying that I should take a knife, go out and stab someone," he told the court.

He later turned himself in to Navy authorities.

The killing caused an international stir, prompting apology visits to Japanese leaders by the U.S. ambassador to Japan, the Navy’s commander in Japan and other military officials.

U.S. personnel at Yokosuka Naval Base underwent a mandated mourning period in the wake of the murder with a curfew and a ban on alcohol sales and consumption.

A representative from Yokosuka Naval Base legal office sat behind Ugbogu on Wednesday. The Navy provides observers for any sailor being tried in Japanese court.

"It’s a case being tried under Japanese law. We have great faith that justice will be served through the Japanese court system," Jon Nylander, a Commander, Naval Forces Japan spokesman, said Tuesday.

If found guilty, Ugbogu faces the death penalty or life in prison.

Murakami said he hoped to get a ruling on his motion for a psychiatric evaluation during Thursday’s session. Regardless, it appears he will mount an elaborate defense. A session was also to be held Friday, with the trial resuming in the new year.

Ugbogu’s mother, a minister living in New Jersey, will be flown in to testify Jan. 13. The next day, Ugbogu, his girlfriend and another U.S. sailor are scheduled to testify.