Mr. Dowd, the lawyer for Ms. Sheehan, said that she had already been examined for more than 10 hours by the prosecution’s psychologist and was eager to answer any other questions the expert had. Mr. Dowd also said that a videotape would show that he and his client had cooperated fully.

As told by the Sheehan children and Ms. Sheehan in interviews, their household was dominated by Mr. Sheehan’s rages. One day, he wanted steak for dinner but found his wife making pasta. He flung the sauce all over the kitchen, Ms. Sheehan said, and her daughter, Jennifer Joyce, recalled that “this pot of boiling sauce went all over my mother.”

On another occasion, Ms. Joyce, a nurse, said, she found her mother pinned to the living room floor as her father punched her. “I started screaming and he left,” Ms. Joyce, 24, said. “I was generally able to get away from him. One time, he knocked down the door to my bedroom. Another time, he caught me, and threw me down.”

In the summer of 2007, the parents, their son, Ray, and another family went on vacation to Jamaica. Ms. Sheehan turned up for dinner with her face battered. “They showed up really late,” Ray said. “He started doing all the talking — saying she tripped in the tub and hit her head. He kept talking over her.”

Ms. Sheehan said that in fact, her husband had smashed her head against a cinder-block wall.

His wife said he would often remind her that he had worked in a crime scene unit and could dispose of her body without leaving evidence. When she went to get her broken nose treated in an emergency room, he waited outside. “He kept calling me from the parking lot, saying that if he saw the police coming, he would kill me and kill them, and go down in a blaze of glory,” she said.

The next morning, he was furious because she refused to go on a Florida vacation with him, Ms. Sheehan said. In his final minutes, she said, he pointed his Glock at her as he shaved, but she had already picked up his revolver. Then she fired at him.