The Long Island man charged with killing his teacher wife choked her to death and then staged an elaborate scene to make it look like she was abducted after her car got a flat tire, police said Thursday.
Nassau County Police Commissioner Lawrence Mulvey told reporters that William Walsh, 29, tried to cover his tracks after he killed Leah Walsh during an argument overnight Saturday.
"We allege that William Walsh choked his wife to death, staged a scene to make it look like her car had gone off the highway ... staged text messages," Mulvey said. "Mr. Walsh should not enjoy one nanosecond of freedom for the rest of his life."
William Walsh was arrested late Wednesday and charged with 29-year-old Leah's murder, two days after she was reported missing.
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His attorney Mark Seman claimed the confession was the result of "at least nine hours of continuous nonstop interrogation."
"This is a case that should have taken weeks to work on, not days," Mark Seman told reporters at his client's arraignment.
"If we know anything from recent events, confessions are inherently unreliable, especially when trickery is involved," he said. When asked to clarify what he meant by trickery, he said, "I am saying unquestionably any confession that they obtain is done by tricks."
Walsh faces 25 years to life in prison, according to Nassau County Det. Lt. John Azzata.
"Mr. Walsh went with a friend to Atlantic City and returned between the hours of 2 and 3 a.m. Sunday," an emotional Azzata told reporters Thursday. "Sometime after that, Mr. Walsh and the victim, Leah, got into an argument. This escalated into a physical confrontation, which escalated into the death of Leah Walsh."
Azzata said the couple's fight was over William Walsh's "possible infidelity" and said Walsh might have had "one girlfriend or several girlfriends."
On Sunday, after allegedly killing Leah, William did his laundry at a nearby Laundromat and even went to McDonald's, according to Azzata.
Then, before dawn on Monday, he took his wife's body from their house, placed it on the floor of the car and drove around Long Island "in the cover of darkness" looking for a spot to dump it, Azzata said.
"Ultimately, he removed Leah from the vehicle, dragged her across the cold ground and left her in weeds," said the homicide detective, his voice catching.
The husband is then believed to have driven the black Ford Focus to a spot along a highway 13 miles away, faking a flat tire by letting the air out, according to Azzata. The tire showed no sign of damage.
Azzata said that a passerby saw a man running from one car to another, yellow car on the roadside early Monday morning and driving away. William Walsh has a yellow car, he said.
The teacher's body was found at 7:57 a.m. Wednesday.
The couple had no history of domestic violence but were separated for a time more than a year ago. William Walsh confessed to the crime after several hours of interrogation, according to Azzata. He has no prior criminal record.
Long before her disappearance and murder, William had been "very abusive" toward his wife and lied to detectives about his marital problems, the New York Post reported Thursday.
Nassau County police said they arrested Walsh because of inconsistencies in his alibi and his story about what had happened to Leah, sources told the Post.
Leah Walsh was planning to divorce her husband, according to friends.
A neighbor of Leah's parents in Rockville Centre, N.Y., said the couple fought constantly when they lived there.
"I heard him being very abusive to her verbally, cursing," the neighbor, who asked not to be identified, told the Post. "Cursing, 'F- - - you!', screaming at the top of his lungs, and she was just very distraught."
The special education teacher's abandoned car was found with a flat tire Monday on a Long Island highway, about 13 miles from another highway where her body was found Wednesday morning.
William Walsh made several tearful public pleas to help find his missing wife, but police said they arrested him after the identity of the body was confirmed Wednesday evening.
Before the discovery of the body, he spoke to reporters outside the couple's Bethpage, N.Y., home and appealed for information about his wife's whereabouts.
"I miss her more than anything," he said, noting her dedication as a teacher. "She loves her children. She wouldn't just leave them. Something had to have happened."
Detectives interviewed the husband on Tuesday, but police said at the time that it was a routine part of the investigation.
The couple had a "huge fight" Saturday night, according to a text message Leah Walsh sent her college friend Lucas Bean.
Bean told the Post that Walsh's husband "went berserk on her" after coming back from a trip to Atlantic City.
Leah was texting Bean during the argument in the car.
"She told me the marriage is over. [She said,] 'I'll tell you why when I talk to you. It's something really, really bad,'" Bean, a friend from the University of Massachusetts Amherst, told the paper.
"[She said] she was definitely getting a divorce," he added. "There was no way she could stay with him after what he'd done. I never found out what it was [about]."
The couple were married for three years and have no children, police said. Her parents declined to speak to reporters.
Leah Walsh worked with autistic children at a private school in Glen Cove. Police believe she usually left for work between 6:15 a.m. and 6:30 a.m.
At about 6:30 a.m. Monday, a state Department of Transportation vehicle left a sticker on the side window of her car indicating it had mechanical problems. The doors were locked, and the woman was nowhere in sight.
FOXNews.com's Catherine Donaldson-Evans and the Associated Press contributed to this report.