Richard Rosenthal was mentally insane when he beat his wife to death and then impaled her heart and lungs on a backyard stake, a defense attorney argued yesterday in Middlesex Superior Court.

Rosenthal, 40 of Framingham, confessed to murdering his wife, Laura Jane, on the evening of Aug. 28, 1995, after she criticized him for burning their dinner. Norman S. Zalkind, his attorney, said Rosenthal had been suffering from mental illness for some time.

"What does a man do who has an argument with his wife? Does he cut her heart and lungs out? It's absolutely insane," Zalkind said. "Does a murderer leave the heart and lungs sticking out of the ground?"

In summations culminating three weeks of arguments, Zalkind told the jury of 10 women and two men that his client was "pushed...over the edge" by the death of his infant son in 1994.

"[Rosenthal] was paranoid, upset that she had changed and was becoming an alien. He didn't recognize her," Zalkind said in a telephone interview yesterday.

Assistant District Attorney Martin Murphy said Rosenthal, a rising financial executive at John Hancock Financial Services, was a calculating killer who is faking mental illness.

"It is a fiction. It is an excuse to justify what he has done," Murphy said. "Mental illness was not in the driver's seat. He was."

Rosenthal sat quietly during the arguments, appearing to smile slightly when Murphy described the couple as having marital problems.

The victim's mother wept through much of the closing arguments.

Arguments ended around 4 p.m., and the jury will return to the court-house in East Cambridge this morning for deliberations.

Kater Re-Tried

Another case yesterday brought 50-year-old Brockton resident James Kater, who has been convicted twice of killing a teenager and tying her to a tree in Freetown State Forest, to court for the fourth time in 17 years.

The Supreme Judicial Court overturned 1979 and 1985 decisions that Kater, a former doughnut shop manager, murdered Mary Lou Arruda, 15, because testimony from hypnotized witnesses was used to identify the model and license plate number of Kater's car.

A third trial, in 1992, ended in a hung jury.

"There never was any physical evidence that Mr. Kater is responsible for this case in any way, shape or form," defense attorney Joseph F. Krowski Sr. said last night. "All the witnesses were hypnotized by an improper technique used by an amateur hypnotist."

Krowski said he planned to introduce new evidence that the teenager was the victim of cult activity. He promised jurors they would hear from a witness who saw more than 20 people carrying torches into the dark woods around the time Arruda was killed.

Prosecutors said cigarette butts and tire tracks linked Kater to the murder and that investigators had discredited Kater's alibi. Prosecutors said they may discuss Kater's previous criminal record showing he abducted a 13-year-old girl who also was tied to a tree with a strap around her neck.

--The Associated Press contributed to the reporting of this story.