Law enforcement sources said yesterday that three of the five persons killed in a Landover apartment Friday allegedly were operatives in a drug distribution network in Northeast, and said the Landover killings could be connected to the scalding and torture of a young suspected drug dealer late last month.

As police identified the dead and began probing their backgrounds, a picture of the drug trade and its Washington underworld was slowly developing.

Most of the Landover victims, Jamaican natives who came to the area from New York, had moved frequently from one apartment complex to another, a pattern seen in other cities as officials try to staunch bloodshed.

Three of them had been arrested in summer after a drug raid in a Northeast Washington apartment that allegedly served as a distrbution center for crack, according to law enforcement sources and court records.

Law enforcement sources said the Landover shooting deaths of four men and a woman represented an escalation of the bitter competition for the newly emerging and highly lucrative crack market in the Washington area.

Investigators had linked those killed in Landover to the Mayfair Mansions and Paradise Manor apartment complexes in Northeast, one of the first teeming crack markets in the area run by Jamaicans.

The drug trade at Mayfair-Paradise apartments also has been marked by violence.

During one six-week period in the fall of 1986, six drug-related murders were reported at the apartments, and in December a D.C. police officer was shot and critically wounded at the apartments, where gunshots routinely ring out.

One apparent skirmish in the on-going Jamaican drug battle was brought into focus by the Landover deaths.

Law enforcement sources said that the slayings were partly in retaliation for the Christmas Eve scalding and torture of Patrick Monfiston, 20, a Jamaican native.

Acting on a noise complaint, police discovered Monfiston, his body badly burned by hot water, in a bathtub in Room 105 at the Regency Congress Inn, 600 New York Ave. NE.

Jamaican drug dealers, who are organized into gangs they call posses, are moving into the Washington area -- often from New York or Miami -- in increasing numbers.

Known for their ruthlessness and territorial violence in defense of their trade, law enforcement sources said, such gangs were believed responsible for 626 murders nationwide, including about two dozen in the Washington area, between January 1985 and July 1987.

Prince George's County police yesterday identified two of the male victims of the Landover shootings as Leonard Francis, 35, and Richard Alexander Williams, 30, both natives of Jamaica whose last known addresses were in Brooklyn, N.Y.

Francis, also known "Chief" and as Peter Hamilton; Williams and another of the shooting victims, Lloyd G. (Donnie) Chambers, 34, of Landover, were arrested in August after police executed a search warrant at 5804 Foote St. NE, law enforcement sources said.

Those three men, at least two other men and a woman allegedly sold crack out of the apartment and at the Mayfair Mansions and Paradise Manor apartment complexes, according to the affidavit filed in support of the application for a search warrant, which was filed in D.C. Superior Court.

After their arrests, the men and a woman, Wanda Summerville, were charged with possession with intent to distribute cocaine.

A federal grand jury in the District was expected to indict the group on what one official said were wider-ranging charges in the coming weeks.

The Foote Street apartment, according to the affidavit, was home to several men who usually answered the door armed with handguns and kept a fully automatic machine gun in a rear bedroom.

In their search, local and federal officers seized five weapons, money, 100 grams of marijuana and 138 grams of a "tan rock substance" resembling crack.

In Landover Friday night, police found the bodies of Francis, Chambers, Williams, Everton Mitchell, 21, of the Bronx, N.Y., and a still unidentified woman in a third-floor apartment at the Village in the Woods complex, 2320 Brightseat Rd. near Landover Mall.

The victims had been shot numerous times in the head and chest, police said.

Officers had been called to the address about 8 p.m. after a sixth victim who survived went to a neighbor's apartment for help.

That woman, whose name has not been released, was listed in serious condition yesterday at Prince George's Hospital Center, where she is recovering under heavy protection by county police from surgery for a bullet wound in the neck, police said.

Three men who were seen leaving the area near the apartment in a red, late-model car are still being sought, said county police, who added that they are close to identifying the three men.

Staff writer Nancy Lewis contributed to this report.