More than half of the 95 slayings in the District this year are drug-related, according to law enforcement officials, a marked increase from last year when about a third of D.C. homicides were drug-related.

Most of the increase results from drug deals gone sour and battles between rival drug dealers, according to police and prosecutors who have expressed grave concern over the escalation of violence. The victims and assailants are typically young men, and the slayings often involve high-powered weapons of a sort seldom seen here previously.

Also counted as "drug-related" are slayings committed by people who are high on mind-altering drugs such as PCP, but the increase in this area has not been as sharp, officials said.

"It's staggering," U.S. Attorney Joseph E. diGenova said. "It's a sign of the intense competition that exists among organizations in the neighborhood drug dealing business, and it is a replication of similar occurrences in other major cities."

As an example of the kinds of slayings the District is seeing, officials point to a shooting March 8 in the last light of a balmy Sunday evening.

A Metrobus stopped to unload passengers in the 2600 block of Martin Luther King Jr. Avenue SE. A red Chevrolet Blazer pulled alongside the bus, boxing in a Toyota, and someone inside the Blazer began firing. Aaron Randoph Davis, 19, allegedly fired a dozen bullets into Michael Oliver Jones and four into Vincent White.

Davis, according to police, was settling a score: Jones, 21, had wounded Davis the night before and had shot to death his 19-year-old roommate.

"It was like 'Miami Vice' {with drug dealers} going up and down Martin Luther King Avenue, selling drugs and shooting themselves," Police Chief Maurice T. Turner Jr. said last week. "That one was so bad that we had to put the entire Emergency Response Team out for {Jones'} wake because the word on the street was that there would be more retaliation."

Drug-related slayings have increased "geometrically" for eight years, and "dramatically" in the last three, diGenova said. Police said they fear that homicides this year will substantially exceed the 196 slayings recorded in the District in 1986.

The increase in drug-related killings is consistent with statistics that reflect soaring drug use in the city, law enforcement officials said. About 30 percent of juveniles facing charges in D.C. Superior Court who have agreed to be tested for illicit drugs since March 1984 have tested positive, according to the D.C. Pretrial Services Agency, which interviews people when they are arrested, tests them for drugs and recommends whether they should be held pending trial.

Of adults facing charges, even a higher percentage have tested positive for drug use. In March, for example, 1,144 of the 1,578 adults tested by the court, or 72 percent, had used drugs. Pretrial Services tests for five illegal drugs, but the most commonly found are PCP and cocaine; about four-fifths of those who test positive for drugs at the court are found to have cocaine, PCP or both in their bloodstreams.

In 1979, drug cases accounted for 20 percent of all misdemeanor and felony cases referred by city police to the U.S. attorney for prosecution. By 1986, drug cases had more than doubled, to 46 percent of all cases referred.

"The murders and the deaths demonstrate clearer than anything can how wrong it is for people to think that drugs are a victimless crime. We've seen as a result of overdose deaths and drug-related murders that that isn't the case," diGenova said.

Many of the drug-related slayings in the District are characterized by the use of high-powered weapons and by the firing of numerous rounds. Victims and suspects tend to be in their late teens or early twenties.

"For lack of a better term, it's the punk factor. You've got younger guys playing the macho bit," said Capt. Larry Soulsby, commander of the homicide squad.

"They carry a big gun, and a lot of times they react violently without thinking of consequences. And they're killing people for very small amounts of drugs and money," Soulsby said.

"Dealers are natural enemies in a narcotic atmosphere. There's increasing tensions to the point that there's almost a day-to-day exchange," said Inspector Nelson Grillo, commander of the D.C. police morals division, which includes the narcotics branch. The homicide squad and the narcotics branch have been working together more than ever this year to solve the cases, according to Grillo and

Soulsby.

Adding to the city's problems, Grillo said, is evidence that several of the slayings this year apparently have involved dealers from New York or other cities.

For example, the middle-class Fort Lincoln neighborhood of Northeast Washington was surprised last month when the bullet-riddled bodies of two men were discovered near a community park. One body was found along a roadside and another in the back seat of a car that had been rented at Los Angeles International Airport.

Both men were in their late twenties and had been shot with a 9mm semiautomatic gun. Police said they found a bottle of PCP in the car and evidence that more drugs had been taken from the trunk.

On Feb. 4, three men argued over drugs in a barren apartment at 2950 Second St. SE that apparently was used only for drug transactions. Roy Davis pulled a gun and shot 22-year-old Robert Newman to death in the apartment, according to police. Then Newman's brother, Paul Newman, 23, allegedly shot Davis to death. When a police investigator switched on a kitchen ceiling light, he saw a shadow and found a packet of drugs hidden in the light.

Last week, a pregnant 26-year-old woman was fatally shot in the 2800 block of Robinson Place SE by a man who fired five shots as she stood in the entrance of an apartment building. Police described the woman, whose name has not been released pending notification of relatives, as Davis' common-law wife and said she apparently had taken over his drug business after his death.

Law enforcement officials have stepped up undercover narcotics operations, including Operation Clean Sweep, which in the last nine months has resulted in 18,000 arrests and the seizure of more that $8 million in illegal drugs. Programs aimed at involving residents, including a confidential tip line to report drug transactions, also help, police said.

But officials say the world of drugs is difficult to infiltrate, making it harder to solve drug-related slayings than other kinds of killings. Of the 95 homicides in the city this year, 64 have been closed by arrests, according to police.

"It's not ruled by a code of silence, it's more a code of self-preservation . . . because a person who knows about narcotics is most often involved himself," Grillo said.