On April 29, an unidentified telephone caller brusquely told a State Department supervisor that Ralph Madden, a communications technician with a high security clearance, was sick and would not report for work that day.

What the mysterious caller did not say was that Madden would never be back on the job again.

The next day, shortly before noon a pedestrian discovered the 46-year-old Madden's fully clothed body lying face down in an isolated field off Stevenson Avenue in Fairfax County, near Alexandria's West End. According to investigators, Madden, who had multiple stab wounds in the chest, had been dead for 24 to 48 hours.

"He may well have been dead at the time this telephone call was received at the State Department," said Fairfax police spokesman Warren Carmichael. aAside from the unexplained call, he said, "There are no clues, no suspects, no leads."

Madden, a $19,500-a-year, middle-level civil servant, had been employed by the State Department since October 1962 and worked in the department's main offices. He was one of about 30 technicians who decode, process, and transcribe overseas cables on a continuous, 24-hour basis, said press spokesmen.

It is a job that can involve "classified data, and Madden had a cryptoclearance for that purpose," said an employe. But the job is dominated by the handling of routine releases that are "very unsexy. Sometimes it's like a glorified mail room," the spokesman said.

"It's a rather curious and interesting homicide, but we're certain that this didn't involve state security," said State Department spokesman David Passage. "The phone call is what's so unusual. There are thousands of extensions in the State Department and you don't call up the right supervisor by sheer happenstance.

"There are leads worth following up right within this building," Passage said. "You have to know a lot about the man, what shift he works and who his supervisor is to make a phone call like that."

No murder weapon has been found, police said. Carmichael added that investigators are still not certain whether Madden was killed at the field, located east of Shirley Highway, or somewhere else.

The dearth of substantive information is so complete, investigators said, that Fairfax police will make Madden's murder their "Crime of the Week" case, a status normally given crimes after month of work when all available leads have been exhausted.

State Department colleagues and Madden's supervisors were keeping quiet about the slaying. "We're refering everybody to the press office or the local police," said State's special agent Don Purser, in charge of the department's investigation.

Passage and Carmichael said Madden, a bachelor, lived alone in the Forest Hills apartment complex at 427 Southern Ave. in Oxon Hill. Detectives have canvassed the neighborhood for clues for the past two days, but Passage said "there is no indication of money problems or anything else."

Several days after the investigation began, Madden's car was discovered by District of Columbia police in a fairly high crime area at the intersection of 24th Street and Benning Road., NE.

One of Madden's neighbors summed up the lack of pertinent iformation on the victim that has thus far hampered the investigation.

"He's tough to describe," said Sheila Jervis, a Forest Hills apartment resident. "You look at some people and think they're aggressive, or compassionate, or something . . . He was just Mr. Madden, even though I used to say hello."