East of Rock Creek Park, on those streets where drugs are openly sold, heroin is referred to as Murder One, or more recently, Black Tape (as in a sign of mourning)--both names testimony to the potency of the deadly white powder that last year claimed a record 115 overdose victims in the nation's capital.

West of the park, from Georgetown to Embassy Row, cocaine is called "snow," a more exclusive "indoor" drug, less deadly but equally worrisome, according to interviews with Washington doctors who specialize in disorders of the nose, drug abuse counselors who operate crisis "hot lines," and police who report that at least three people died last year of cocaine overdoses.

Just as the park is a major dividing line economically and culturally between Washington life styles, it's also a border between drug cultures divided by income and race--with mostly a desire for the high life on one side, and a struggle for survival on the other. Virtually all heroin overdoses last year occurred east of the park, while the major cocaine confiscations and all the cocaine-related deaths occurred to the west.

"When you're talking about cocaine, you're talking big money, diplomatic couriers, white people having fun," said Joe Wright, director of information and referrals for the Washington Area Council on Alcoholism and Drug Abuse. "Over in the ghetto, you're talking about a tremendous increase in the availability of high-quality heroin that invariably seems to accompany hard times."

Of the 115 heroin overdose deaths last year--up from 85 in 1980--111 were from heroin use alone; three involved heroin in combination with methadone, and one was in combination with the depressant Dilaudin. According to Medical Examiner James Luke, autopsies are revealing that overdose victims are also using high levels of alcohol.

"The thing that's causing overdoses is competition between drug dealers," said Sgt. Roy Crogan, a narcotics detective who works out of the 3rd District police station, which covers the 14th Street strip. "It's like a gas war. The prices are coming down and the quality is going up."

Police say 6,470 people were arrested for narcotics-related violations last year compared with 5,103 in 1980, the overwhelming majority of them young black men who lived in the Shaw and Cardozo neighborhoods and areas east of the Anacostia River. Drug use was involved in many burglaries, robberies, thefts, assaults and murders committed last year, officers say.

In 1981 police confiscated 12 pounds of heroin in Washington--most of it around 14th and U streets NW--that tested from the usual 1 percent purity to a virtually unheard of high of 10 percent: the "Murder One."

Five pounds of cocaine were seized by police, the biggest catches coming from three raids, all west of Rock Creek Park.

That this is a tale of two drug towns is best illustrated by narcotics officers who work both sides of Rock Creek Park.

"It's two different worlds and they never meet," said John Centrella, a D.C. narcotics detective who spent several months last year staking out the $1,500-a-month Georgetown Mews apartment to which William Finebloom, the 38-year-old son of a well-known New York ophthalmologist, allegedly imported 28 pounds of pure cocaine from Peru between April 1980 and July 1981.

When he was arrested last July, Finebloom had in his possession an ounce of cocaine that tested out at 98 percent pure. He was recently convicted of possessing cocaine and sentenced to seven years at Allenwood federal prison in Pennsylvania.

"He would hold up a rock big as a half-dollar and let the light hit it so you could see the crystal lines in it," Centrella said of Finebloom. "He would smile and say, 'Right off the boat.' And if he liked you, he'd give it away. It was no problem for him. He could turn over four kilos in two days."

Most of the white dealers in affluent neighborhoods are "not really street-wise," said Ronnie Hairston, another D.C. narcotics detective who spends much of his time tracking drugs in black areas such as the 14th Street strip and the Shaw and Cardozo neighborhoods.

"They feel there is honor among thieves," he said. "They'll brag and say, 'Hey, this is pure' and they'll stand behind the product, even give you a refund. In a black area, you can end up buying a bunch of baking soda and you better not try to take it back."

Last October, Hairston participated in a raid on Kim's Liquor Store at 3010 14th St. NW--one of those tough areas he was talking about. Kim's is distinquished by large red letters on the front that read: LIQUOR. The area is crowded with low-income apartments and elderly residents can be seen hobbling on canes up to the front counter, which is shielded by bullet-resistant plexiglass, to buy their usual half pints. Outside youths in knit hats and short leather jackets mill and roam.

During the police raid on Kim's, the youth working behind the counter was doing a bustling business for that side of town. He had nearly $1,000 in 10's and 20's stuck in his pants and shirt pockets, plus five "Sno Seals" containing cocaine that police found to be almost 12 percent pure, authorities said.

"A black dealer will make as much as he can from a small amount," Hairston said. "If it is 20 percent, the black dealer will kick it down to 12 percent, bag it in half grams and sell to somebody who may try to do the same thing again."

"This is not 'trickle down' coke from Peru," he added. "The coke in Shaw most likely comes from New York with a shipment of heroin and pills, and the coke has probably been jumped on cut , stepped on and stomped again."

It takes extraordinarily high-quality cocaine to cause an overdose, and death can occur from simple snorting as well as smoking or injecting the drug. The effect of the drug is to restrict blood flow and breathing.

"The first thing that happens is that a person gets real talkative, excited, then the next thing you know they are having a seizure," said Dr. David Fairbanks, an ear, nose and throat specialist with George Washington University Hospital. "After the seizure they probably won't be breathing."

More common than cocaine overdoses, however, is the occurrence of what is known as "coke nose," said Fairbanks.

"There is nothing in Washington to compare with what is happening in Los Angeles, but there is an increase," he added. "You get crusting and scab on the inside of the nose and the raw edges tend to bleed. Some people also begin to whistle when they breathe. I had one government worker who sat near the water cooler in his office and he had to hold his breath so he wouldn't offend the secretaries who came for a drink."

Fairbanks noted that the dangers of cocaine have been well documented since the turn of the century, and added ruefully, "I can tell you that many lives are being destroyed by cocaine."

Joe Wright of WACADA, which operates a 24-hour drug crisis hot line in the Washington area, said that smoking cocaine or "free basing," as it is called, is resulting in numerous calls from people who can't sleep, become paranoid and begin hallucinating. Wright adds that many callers also complain of financial disaster brought on by rapid addiction to smoking "free base."

"It's anything but 'free,' " said Wright. "Our increase in calls is the direct result of more drugs being available. When the drugs start hitting the street, the more people you have with problems. There is so much out there that people who ordinarily wouldn't be involved are now starting to get caught up in it."