ANNAPOLIS, NOV. 19 -- A Maryland appeals court today overturned the conviction of a Montgomery County man who was found guilty of killing his common-law wife even though her body was never recovered.

In reversing the conviction of Gregory Tu, 60, the Court of Special Appeals ruled that evidence seized from a Las Vegas hotel room that Tu rented after his wife's July 1988 disappearance was improperly admitted at his trial last year.

Although detectives had a search warrant, the items they confiscated from the room had not been listed on it in advance. For that reason, the court said, prosecutors had to prove that the evidence, including documents showing Tu had used a false name in Nevada, was collected legally.

But because Circuit Judge William Cave did not require investigators to testify about the conditions under which they found the evidence before he denied a defense motion to suppress it, Tu must be given a new trial or released, the court said. Tu is serving a life sentence for the first-degree murder of his wife, Lisa, 41.

Assistant Attorney General Richard Rosenblatt said today that the state will probably appeal to Maryland's highest court. "It's clear the state does have the burden of proof when it comes to warrantless seizures, but we felt we satisfied it in this case by presenting the evidence itself," which was similar in nature and location to what was listed on the warrant, he said.

Tu, a former Washington restaurant manager, was the first person in Maryland convicted of first-degree murder despite the absence of a body. Police and prosecutors maintain that Tu was a money-strapped gambler who killed his wife as she slept on a couch in their Rockville home to obtain $200,000 from her life insurance policy and because she was having an affair.

His two-week trial relied almost exclusively on circumstantial evidence, including testimony from a garbage hauler Tu had paid to remove the couch, documents allegedly showing that Tu had forged his wife's name to withdraw $44,000 from her bank account, and an analysis of bloodstains found in their home.

The evidence in question in today's ruling was recovered from the hotel room where Tu stayed in August 1988 just before he was scheduled to take a polygraph exam about his missing wife.

In addition to the documents showing that Tu had assumed a false indentity, items taken included a keno card, a communication with a prostitute, condoms, checks allegedly drawn on money stolen from his wife, and an airplane ticket to Pensacola, Fla.

During the trial, prosecutors used the evidence to bolster their contention that Tu was trying to establish a new identity and "that finding his wife was the farthest thing from his mind," according to the court's 21-page opinion.

Attorneys for the two sides disagreed today about the importance of the Nevada evidence. "It was very important to the state's case," said Paul DeWolfe, one of the attorneys who represented Tu at his trial. "The government made much of his time in Las Vegas to show that he was not that concerned about his wife's whereabouts."

But Assistant State's Attorney John McCarthy said the documents "were a small part of a much bigger picture."

Rosenblatt said it is unclear whether the state would be prohibited from using the questionable evidence during a new trial or whether a more complete hearing on it would satisfy the court.