Kevin P. Mulcahy, a former CIA technician who first tipped the agency to alleged arms dealing and terrorist training in Libya by Edwin P. Wilson and other former CIA agents, was found dead yesterday at a motel in rural Shenandoah County, Va.

Mulcahy, 39, who had become obsessed with pursuit of the case against Wilson, was scheduled to appear as a witness next month at Wilson's trial here on charges he shipped explosives to Libyan ruler Col. Muammar Qaddafi.

Mulcahy's body reportedly was discovered about 8 a.m. slumped outside the locked door of a cottage he had rented at the Mountain View Motel Court near Woodstock, about 90 miles west of Washington.

The 47-year-old motel, a collection of eight small, white cottages off Rte. 11 in a desolate section of the Blue Ridge Mountains, is occupied largely by construction workers who pay $50-a-week rent.

He was the second potential witness in the government's case against Wilson to die. Earlier this year, a Cuban who allegedly met with Wilson in Geneva to discuss a purported assassination plot was killed in a boat explosion in Miami. The blast later was ruled an accident.

Assistant U.S. Attorney E. Lawrence Barcella, the prosecutor in charge of the Wilson case, said last night he had been informed by Virginia authorities that "from an external examination of the body there doesn't appear to be any foul play." There were no visible wounds or injuries, Barcella said he was told.

Mulcahy's death "will not affect our ability to go to trial," Barcella added.

The Associated Press quoted a deputy sheriff last night as theorizing that Mulcahy, who had continuing bouts with alcoholism, may have died from exposure during overnight temperatures that dipped into the 40s. The law officer was quoted has having been told by one motel resident that Mulcahy had been drinking heavily and had tried without success to enter his room.

The AP said the deputy told them Mulcahy had checked into the motel Oct. 20 and was ordered to leave Monday because he had been drinking and glass in his door had been shot out with a shotgun. The officer said he believed Mulcahy did the shooting.

He had been dead several hours when his body was found by another motel resident, the deputy said. The officer quoted the resident as saying that Mulcahy was "real staggery" on Monday and was last seen alive in his pickup truck, often slumping over its steering wheel.

Mulcahy's body was transported by rescue squad members to Shenandoah County Memorial Hospital in Woodstock. It was later transferred to Fairfax Hospital, where an autopsy is scheduled for today, an employe in the state medical examiner's office said.

Mulcahy, the son of a career CIA official, was credited with triggering the agency's investigation of Wilson and others allegedly aiding Libyan terrorist activities in a telephone call to agency headquarters in Langley during Labor Day weekend in 1976. Pursuing and monitoring the investigation became Mulcahy's personal quest. In an interview last spring, he said he had guided news reporters on foreign expeditions to interview witnesses in the case and he himself--using a $5 police badge he purchased in Times Square -- had interviewed 40 witnesess posing as an FBI agent.

He had resigned in 1968 from his job as a CIA communications expert and in 1976 joined Wilson, ex-agent Francis E. Terpil and others in the Libya project, claiming he thought the activities had the agency's blessing.

Mulcahy said he later split from Wilson after Wilson ordered him to procure a heat-seeking Redeye missile for the Libyans from General Dynamics Corp. Mulcahy said he was concerned the missile might be used in a terrorist attack on a commercial jetliner.

Wilson, 54, was lured from Libya earlier this year by U.S. law enforcement officers and is in custody in lieu of $60 million bond. He is scheduled to go on trial later in Houston on separate charges related to illegal explosives shipments. A third trial, on firearms charges, is set to begin Nov. 15 in Alexandria.

No date has been set for yet another trial in the District on charges Wilson and Terpil conspired to kill a Libyan dissident on Qaddafi's behalf.

The public learned about Mulcahy in June 1981 in two dramatic articles by investigative reporter Seymour Hersh in the New York Times Magazine. Hersh's detailed account of Mulcahy's involvement with Wilson and Terpil in the sale of high explosives, sophisticated weaponry and commando training services reinvigorated and expanded the federal investigation of Wilson's activities.

In recent months, Mulcahy had been working to secure the return from Spain of George G. Korkala, a former Terpil associate who was convicted in 1981 in absentia in New York for trying to sell 10,000 machine guns to New York detectives posing as South American terrorists.

Mulcahy has also traveled regularly to the West Coast where a film production company has purchased the rights to his life story, according to Charles Fries of Charles Fries Productions Inc.