WOBURN, Mass. -- Did growing debt and dissatisfaction in his sex life drive Neil Entwistle to kill his family? Did Rachel Entwistle kill her baby before turning the gun on herself? Those are the opposing arguments that the jury in the Neil Entwistle double-murder case will be weighing when they start deliberating on Tuesday.

Entwistle Case Goes To Jury

After listening to 12 days of testimony from family members, friends and investigators, the jury heard closing arguments from both the defense and prosecution teams on Monday. The British man's defense team rested its case without calling a single witness.

Entwistle, 29, is accused of first-degree murder in the shooting deaths of his wife, Rachel, 27, and their 9-month-old daughter, Lillian Rose, in the family's rented Hopkinton home in January 2006.

In closing arguments, defense attorney Elliot Weinstein said Entwistle wanted to "protect" his wife's honor and cover up her suicide after he found Rachel and Lillian dead with his father-in-law's gun on the bed.

"First Rachel put Lillian over where she thought her heart was and shot her. Then she pointed the gun toward her head, steadied it with both hands and fired," Weinstein said.

Weinstein told jurors that Entwistle took the gun and drove more than 50 miles from Hopkinton to his father-in-law's Carver home to return it because he was "committed to not betraying Rachel's memory."

"In those moments, he knew what he had to do and what he couldn't do. He had to get the .22 back to Carver and he couldn't call the police because he couldn't tell them what Rachel did," Weinstein said.

Police later determined it was the gun used to kill mother and daughter.

In its closing arguments, the prosecution refuted the defense's argument saying the murder-suicide defense theory "doesn't make common sense." Assistant Middlesex District Attorney Michael Fabbri said Rachel was happy to be back at home in the United States with her family and friends.

"She was happy. She had no reason to commit suicide," Fabbri said.

Prosecutors said Entwistle had no money, no job and no friends in the United States. They say Entwistle killed his wife and daughter months after he began looking for sex partners online.

The medical examiner said Rachel died of a gunshot wound at her hairline. Lillian Rose suffered massive internal injuries from a bullet that entered her chest, exited out the back and lodged in her mother's left breast, the medical examiner said.

"I suggest that she might not even have known how to load (the gun) and handle it -- but he did," Fabbri said, pointing at Entwistle.

Prosecutors finished presenting their evidence against Entwistle on Monday with a 45-minute police recording of a police officer telling Entwistle that authorities had found his wife and daughter dead of gunshot wounds. On the recording, Entwistle asks if the two suffered.

"I can't tell you that, but I can probably tell you that it was probably quick," State Police Sgt. Robert Manning said. "I don't think they suffered much."

Earlier in the trial, the jury heard another taped conversation between Entwistle and Manning during which Entwistle said on the morning of Jan. 20, 2006, he left his wife and daughter cuddled together in bed to go shopping. He said he returned two hours later to find them dead.

Entwistle told Manning that he thought his wife and daughter had been shot, but left the house without calling for an ambulance because it was "obvious" they were dead.

"When I saw Lilly, you know, that's when I could see what happened," Entwistle said on the tape.

Entwistle said he then drove to the home of Rachel's mother and stepfather in Carver to find a gun to kill himself, but was unable to get into the house. He eventually ended up at Logan International Airport in Boston, where he said he wandered around the terminals, left, then returned again. He said he decided to fly home to England to be with his parents.

Entwistle was arrested near his family's home in England a few weeks later.

The jury will start deliberating Tuesday at 9 a.m.