Melvin B. Coley, a community organizer for the United Planning Organization, the District of Columbia's antipoverty agency, is being sought by federal agents and law enforcement officers from Washington and Phoenix, Ariz. on a fuigitive warrant charging him with the homicides of three persons in the Arizona desert on Dec. 11.

Representatives of the FBI, the D.C. police Department's fugitive squad and the Maricopa County (Phoenix) sheriff's office met here yesterday to coordinate plans to find Coley, 34. He was last seen on Dec. 16 walking away from the Red Cross station wagon he had been driving as a volunteer.

Coley is accused in the fugitive warrant of murdering William C. Varner, 32, of Phoenix, and Eduardo E. Ortez, 28, and Carlos E. Elsy, 32, both of Tucson.

The bodies of the three men were found in the trunk of Ortez's car by Maricopa County authorities the night of Dec. 11 outside the desert tow of Queen City. All had been shot several times and the car had been set afire.

Authorities said that the shootings occurred at a location far from where the burned vehicle eventually was found.

D.C. police said that Coley was arrested with Varner in Arizona in early 1977 on drug charges, both of which were dropped.

Friends of Coley told police that on Dec. 14 - three days after police say he murdered three men - he played Santa Claus at a St. Elizabeths Hospital Christmas party.

Friends and Coley's wife Lucy, who lives with their 3-year-old son in Northeast Washington, told police that he had done volunteer work for accident and fire victims for years.

Police here said that Coley was listed as a wanted man by Arizona authorities shortly after the bodies were discovered. In their efforts to find him here, D.C. officers said, they conducted a series of raids on residences that Coley was known to have occupied, as well as the UPO facility on Martin Luther King Avenue SE where he worked.

In one raid Dec. 16 in the unit block of T Street NE, police said they found two pistols, more than 900 rounds of ammunition, $50,000 worth of PCP, an hallucinogenic, and a vehicle containing several items. Some of these items, they said, have been identified as stolen.

Police said they were seeking two other men in the homicides, both of whom are believed to have fled the Phoenix area the night of the stayings in a white auto bearing license plates.