YOKOHAMA, Japan — U.S. Navy Seaman Olatunbosun Ugbogu apologized in court Wednesday for fatally stabbing a taxi driver last year, but reiterated that voices in his head forced him to do it.

Defense attorney Yasutoshi Murakami examined Ugbogu and asked several questions about the sailor’s difficult upbringing, as well as his mental state.

Ugbogu, a Nigerian national, told the court he grew up without a father and felt abandoned by his mother when she moved to the United States, although she later sent for him.

He also said that the doctor at the prison where Ugbogu is being held had prescribed anti-psychotic medication to be taken four times daily.

When Murakami asked Ugbogu what he had been diagnosed with, Ugbogu responded, "he said something was wrong with my brain."

During a hearing last month, a court-appointed professor of neuropsychiatry testified that while Ugbogu may be suffering from dissociative amnesia, he did not believe that Ugbogu’s alleged voices made him kill 61-year-old taxi driver Masaaki Takahashi on March 19, 2008.

Ugbogu stabbed the driver after racking up a 19,560 yen (about $200) fare from Tokyo to near Yokosuka Naval Base.

Ugbogu’s mother offered to apologize and reimburse the taxi company for the fare, but the company refused, it was revealed Wednesday.

Prosecutors asked Ugbogu why he would listen to the alleged voices in his head and whether they ever told him to do good things.

Ugbogu said that the voices were only threatening.

"They could do anything, like kill my mother, kill me," Ugbogu said.

Ugbogu was more responsive than in past hearings; however, his eyes appeared glazed and he still spoke in short, hushed tones.

When asked if he had anything else to say following cross-examination, Ugbogu again kept his response brief.

"I’m sorry. I’m ready to show remorse," he said.

Closing arguments are scheduled for July 17.

Stars and Stripes reporter Hana Kusumoto contributed to this story.