Everyone agreed yesterday that what James Baldwin Jr. did to his roommate last year sounds crazy -- that he fatally stabbed his housemate whose beheaded, eviscerated and dismembered body was found two years ago buried in a shallow grave in Collier.

"The question is: Was James Baldwin insane at the time he committed these acts?" defense attorney John Elash said in opening remarks to a jury yesterday at the start of Mr. Baldwin's trial.

Deputy District Attorney Janet Necessary told the jury she would show, through testimony of psychiatrist Dr. Bruce Wright, that Mr. Baldwin, 24, was in his right mind when he killed Brendon Martin, 19, on the night of Jan. 25, 2006.

The defendant's mental state deteriorated over the months he spent in the Allegheny County Jail while awaiting trial on charges of homicide and abuse of a corpse, Ms. Necessary said in her opening statement.

Mr. Elash, however, argued that his client's illogical behavior that night followed a logical course.

The lawyer pointed to Mr. Baldwin's father and namesake, having him stand in the courtroom of Common Pleas Judge Kathleen A. Durkin.

"His dad home-schooled James Baldwin," Mr. Elash said, pointing at a slouched Mr. Baldwin Sr. "You'll hear about how [the son] was abused, about how he was tortured by that man back there."

With his client's upbringing as a backdrop, Mr. Elash explained that Mr. Baldwin had to have been insane to do what he did, the way that he did it.

Ms. Necessary told the jury Mr. Baldwin first denied even knowing the whereabouts of Mr. Martin after county homicide detectives questioned him about the five garbage bags containing body parts, cutting tools, a shovel and household garbage.

They had been led to the items by a Collier road maintenance worker who discovered suspicious bicycle tracks in the snow and footprints that led to the shallow grave about 50 yards off Ridge Road in an isolated, wooded area of the township.

Mr. Martin's remains were positively identified by a tattoo.

Detectives were led to Mr. Baldwin by a piece of homework paper found at the burial site in a backpack. The paper had the suspect's name on it. He and Mr. Martin were college students at the time.

Mr. Baldwin told police that he and Mr. Martin argued and fought on the night of Jan. 25, 2006, because Mr. Baldwin had taken steps to have his roommate evicted, Ms. Necessary said.

Mr. Baldwin said Mr. Martin annoyed him by smoking pot in their Carnegie residence, and by mistreating Mr. Baldwin's girlfriend who, with her young child, lived with them.

Mr. Martin attacked Mr. Baldwin with a hammer, and the suspect reacted by picking up a 12-inch survival knife from the floor. He said he stabbed Mr. Martin about the head and neck, the prosecutor said.

As the victim lay on the floor struggling to breathe, Mr. Baldwin said he decided to kill his roommate by stabbing him in the heart.

After the dismemberment and discarding of the remains, Mr. Baldwin returned home and cleaned up the scene of the slaying.

"He cut up his roommate. This is insanity," Mr. Elash told the jury, explaining it as a legal term distinguishable from medical diagnoses such as schizophrenia or bipolar disease.

Mr. Baldwin either didn't know what he was doing, or he didn't know that what he was doing was wrong, the two-pronged legal definition of insanity, Mr. Elash said.

Dr. Laslo Petras, a forensic psychiatrist at Mayview State Hospital, is expected to testify that Mr. Baldwin has been insane for some time, Mr. Elash said. Dr. Petras observed Mr. Baldwin almost daily over more than a year following the arrest two years ago.

Judge Durkin said testimony should end today, followed by closing arguments by the two attorneys.