The defense lawyers trying to clear Richard Lapointe of a horrendous 1987 murder began an attack in court Friday on a detective who they said secured the mentally disabled man’s questionable confession after a series of suggestive and, at times, threatening interrogations.

Much of the testimony Friday focused on a secretly recorded police interview of Lapointe’s ex-wife, Karen Martin, who also is disabled. On the recording, former Manchester police Det. Michael Morrissey told her that she could be charged with hindering prosecution and lose custody of her preteen son unless she provided him with “some very important details.”

When he testified later in the day, Morrissey defended the interview of Martin. He said she had previously untracked the murder investigation by withholding information. If his questions were at times deceptive, he said, that was an acceptable method of directing her to become forthcoming. He said it was clear to him at the time of the interview that Lapointe, 64, would be charged and custody could become an issue.

“That was in no way a threat,” Morrissey testified. “That was a real-life scenario.”

In a long question and answer session with Morrissey that is scheduled to continue when the hearing resumes July 6, Lapointe lawyer Paul Casteleiro of New Jersey elicited responses that also showed the Manchester Police Department charged Lapointe with murder even though it had evidence that contradicted key points in the confession he ultimately gave to Morrissey.

In the confession, Lapointe said he raped and stabbed 88-year-old Bernice Martin, his then-wife’s grandmother, on her living room couch. Lapointe said in the confession she was wearing a pink housedress.

In his questions, Casteleiro asserted that the Manchester Police Department had collected evidence prior to the confession that supported an alternative scenario. Among other things, Casteleiro said police had information that:

•A witness who saw Bernice Martin perhaps two hours before her death said she was wearing dark slacks and a blue sweater.

•Police found clothing similar to that described by the witness thrown beside Bernice Martin’s bed, as well as a blouse from which the buttons had been ripped.

•Crime scene blood evidence suggested Bernice Martin was not stabbed on her couch, but on her bed, where a knife was found in bloody bed linen.

•Police did not locate a pink housedress.

Morrissey said he either wasn’t aware of the contradictory evidence or wasn’t aware of its significance during his three- or four-hour interview with Lapointe that led to the confession.

Lapointe is accused of raping and stabbing Bernice Martin on March 8, 1987, and then trying to burn down her house in Manchester. He was convicted on July 30, 1992, and is serving a life sentence without the possibility of parole.

The habeas corpus hearing in Tolland County Superior Court this week is an effort by Lapointe’s lawyers to get him a new trial. The hearing before Judge John J. Nazzaro could be his last chance. So far, he has lost all appeals and two prior attempts to win new trials.

Lapointe behaved as if he were oblivious to the significance of the proceedings. He is a tiny man with an oversize head. He wears thick, dark eyeglasses; hearing aids and a jaunty mustache. All day long, he doodled with a pencil or strained over a book of word puzzles. He was dressed in an orange prison jumpsuit so bright it looked as if it were glowing.

Lapointe was a dishwasher until his arrest. He was born with Dandy Walker syndrome, a rare hereditary condition. In his case, it was diagnosed too late to be corrected. The condition causes parts of the brain to develop abnormally. It can lead to hydrocephalus, or water on the brain, which can inhibit coordination, speech, memory and abstract thinking. Friends say Lapointe is absurdly gullible and susceptible to suggestion. His lawyers are arguing that quality caused him to confess to crimes he did not commit.

His ex-wife, Karen Martin, also seemed lost at times in the complexity of the legal give-and-take. She has cerebral palsy and testified Friday that she had been suffering from seizures when she was questioned and secretly recorded by Morrissey — a recording that the police did not disclose until mid-January 1992, more than two years after it was made and after a hearing on whether any prosecution evidence at Lapointe’s initial trial should be suppressed.

Martin is unsteady on her feet and walks with a cane. She has a thick head of bobbed, gray hair and sat hunched over in the witness box. She spoke unsteadily and complained repeatedly that Morrissey tried to suggest to her what her answers should be.

“Did you feel he wanted you to give certain answers?” Casteleiro asked.

“Yes I did,” she answered. “And he kept going over the answers several times. The same thing.”

The questions to Martin, by both Casteleiro and state prosecutor Michael O’Hare, focused on Lapointe’s whereabouts at the time of the murder. Casteleiro is arguing that the police and prosecution in Lapointe’s original trial improperly withheld investigative notes on the duration of the fire at Bernice Martin’s apartment. If, as the notes speculate, the fire burned for 30 or 40 minutes, Casteleiro argues that Lapointe can prove he was at home with his family in their Manchester condo when the fire started.

In her interview with Morrissey and again in court on Friday, Karen Martin said that, with the exception of a period of time that could have stretched to 45 minutes, Lapointe was with her and their son when the murder and arson are believed to have occurred.

During that stretch of 45 minutes or so, Karen Martin said, she was upstairs in the couple’s home bathing her son. She said she assumed Lapointe was elsewhere in the home, but she acknowledged he could have left to walk the family dog without her knowledge.

The prosecution is arguing that Lapointe raped and killed Bernice Martin and set her house on fire while his ex-wife was bathing their son.