Sporadic violence on New Year's Eve left three men dead in Prince George's County and a fourth dead in the District. Another man was killed in the District last night.

One of the Prince George's slayings occurred in a quiet residential neighborhood in Colmar Manor, where a dispute erupted at a New Year's Eve party. Police say two other people were shot in the incident.

In the city, police found the first homicide victim of the new year in an alley in Petworth, a Northwest neighborhood plagued by illegal drug markets.

The unidentified man, shot in the head and back, may have been killed at another location, then left in the alley behind a row of well-kept, two-story brick houses in the 600 block of Longfellow Street NW, police said.

Last night's killing occurred in an alley in the Trinidad neighborhood of Northeast, where a man was fatally shot in the head, police said.

A detective said the man, whose name was withheld pending notification of relatives, was shot about 9:45 p.m. behind Morse Avenue, near the intersection with Trinidad Avenue.

Prince George's police said the county's first New Year's Eve slaying occurred shortly after 10 p.m. in the 6500 block of Hil-Mar Drive in Forestville. The victim, Kevin Patrick Gause, 26, of the 4200 block of South 31st Street, Arlington, was leaving an apartment when gunfire erupted in the parking lot.

Gause was shot several times. Neighbors saw two unidentified men fleeing the scene, police said.

Shortly after 11 p.m., Ben Rouse III, 20, of the 3700 block of 35th Street, Mount Rainier, was killed during a dispute at a New Year's Eve party in the 4300 block of Monroe Street in Colmar Manor.

Police said Rouse and two male friends, whose names have not been released, began arguing with a teenager known as "Larry." Authorities said a young man, who has not been found, shot Rouse and his two friends. One friend was listed in stable condition at Prince George's Hospital Center yesterday, and the other was listed in serious condition.

About 12:15 a.m., an unidentified man was seen staggering down Emo Street near Drum Avenue in Capitol Heights. Police said he had been stabbed twice, and was pronounced dead at Prince George's Hospital Center.

Meanwhile, the District's 483rd and last homicide victim of 1990, Darryl T. Morgan, 19, of the 1300 block of Columbia Road NW, died Monday of gunshot wounds at Washington Hospital Center. He had been found Sunday evening in a parked car in the 5000 block of New Hampshire Avenue NW.

In the District, both the first slaying of 1991 and the last of 1990 occurred in Petworth, the same neighborhood where double execution-style murders in October led D.C. Police Chief Isaac Fulwood Jr. to create a 100-officer task force to target such troubled areas to prevent crime.

Fulwood said at the time that the problem of drug-related violence would not be solved until residents got angry.

Pamela McKee, president of the Kennedy Street Association of Merchants and Professionals, said yesterday, "The community has done its part."