SPOKANE, Wash. (AP) _ An attorney who committed suicide was a key witness in a weapons-possession case against a man under investigation in the Green River serial killings, a prosecutor said Wednesday.

Police Sgt. Gene Ziegler said Dale Wells died of a self-inflicted shotgun wound to the head sometime between Saturday morning and Tuesday morning.

Wells, a deputy public defender for Spokane County, was a law school classmate of William J. Stevens II, who has been described by the Green River Task Force as a ''viable suspect'' in the serial killings of as many as 48 women in the Pacific Northwest from 1982 to 1984.

Stevens has not been charged in the killings.

Ron Skibbie, an assistant U.S. attorney, said Wells gave two handguns to Stevens, inluding a .45-caliber Colt that is the basis for a federal charge against Stevens accusing him of possessing a firearm while a fugitive.

Stevens finished serving a King County sentence for burglary and escape on Monday before being brought to Spokane to face the federal charge on Tuesday. He walked away from a Seattle work-release center in 1981 and remained a fugitive until his arrest in January.

A plea of innocent was entered for Stevens during an initial appearance before U.S. Magistrate James B. Hovis on Tuesday. Stevens was ordered held without bail, but his court-appointed attorney, Roger Peven, said he would request a bail hearing this week.

Peven said he hasn't had time to consider the impact Wells' death would have on the case. He said Stevens was saddened upon learning of the death of his former classmate at Gonzaga Univeristy's School of Law.

''He and Dale Wells were good friends in law school. His feeling was much like that of others who knew Dale; a real sense of tragedy,'' Peven said.

Skibbie called Wells ''a very important witness'' in the firearms case.

''We're still investigating the ramifications'' of his death to the case, Skibbie said, declining further comment.

Skibbie said Wells was not under investigation. He had told investigators he did not know Stevens was a fugitive when he gave him the guns.

Twenty-three guns were found in Steven's possession when he was arrested.