Federal and local law enforcement officers arrested yesterday the alleged leader and nine alleged operatives of what authorities said is a local drug ring that in 2 1/2 years has smuggled $30 million worth of extremely high grade heroin from the opium fields of Southeast Asia to the streets of Washington.

Police and federal agents arrested the alleged drug ring leader, Linwood Gray, a muscular, 34-year-old, former mental patient, shortly after midnight in a dimly lit parking lot in Oxon Hill. Aughorities alleged that Gray had gone there to meet two couriers who had just arrived from Amsterdam, Holland, where they made a drug purchase.

Aughorities arrested two other men at the scene, and seven other persons through the night. They were all accused in an affidavit of being a part of an international heroin smuggling ring that law enforcement sources said is the largest ever uncovered here.

At least 100 pounds of 90 percent pure heroin has been traced to the ring by federal and local law enforcement officials who have been tracking the operation for 15 months. The street value of that heroin, they said, is worth at least $30 million.

The arrests culminated the drug investigation that Assistant U.S. Attorney Barry M. Leibowitz was leading when he was shot and wounded as he walked to the U.S. Courthouse here last month. Earl J. Silbert, the U.S. attorney, said yesterday that investigators are assuming the shooting was tied to the probe of the smuggling ring.

According to law enforcement sources, the alleged Gray ring had contacts with drug suppliers and couriers that long have been entrenched in Thailand, Turkey, Amsterdam and other major Western European cities. The alleged ring also dealt with some operatives from the notorious French connection, the sources said.

The heroin was brought into Washington by couriers flying firs class, who often concealed the heroin the cigarette packs according to the affidavit filed in support of the arrest warrants.

In what Silbert described as the most extensive drug investigation here in memory, a task force of federal Drug Enforcement Administration agents, District of Columbia police and federal prosecutors used surveillance and informants to trace the ring. According to the affidavit, members of the alleged drug organization used aliases, false passports, post office boxes and numerous residences and automobiles in order to obscure their identity.

They bought houses in cash for themselves and their relatives, all paid for in small bills, and bestowed tens of thousands of dollars at a time on drug couriers and drug buyers heading overseas from the District of Columbia, sources said. The profit from these drug sales went back through the pipeline, enriching each partner, according to law enforcement sources.

According to the affidavit, Internal Revenue Service agents were able to determine that Gray bought three houses for a total of almost $200,000, and had paid for them in cash. He used small bills to pay for a $20,000 car and an $8,000 car.

Kenneth Michael Robinson, Gray's attorney, said last night that his client was innocent of all charges. Gray, Robinson said, is an employe of the Club Camelot. at 3859 Alabama Ave. SE., and makes about $14,000 year.

Federal authorities, in their affidavit, alleged that the Club Camelot was a front for the ring's drug dealings.

According to neighbors interviewed yesterday, those arrested managed to blend into an inconspicuous middleclass life style in Southeast Washington and Prince George's County. They lived in modest one-story brick and frame houses, and high-rise apartments with addresses in such places as Hillcrest Heights, Forestville, Morningside and Suitland.

Among those arrested yesterday were people who listed their occupations as mailman, musician, handyman, barber, restaurateur and manpower development specialist. All are now charged with conspiracy to violate federal drug laws.

Arrested with Gray yesterday were Joseph F. Wilson nicknamed "Joe Nose", 42, of 6128 Surrey Square La., Forestville, described by lawmen as a lieutenant of Gray, and Smith D. h/ammond, 21, of Chicago, one of the alleged couriers who met Gray in the parking lot yesterday.

Others arrested included Darlene B. Flemings, 23, of 6403 Pine Lane Dr., Morningside, who lived at the same residence as Gray and was described by law enforcement sources as his girlfriend; Barbara Ann Greer, 32, of 2201 Columbia Pl., Lanover, described as Gray's sister; Alton B. Nelson, 33, of 2425 Naylor Rd. SE; Robert L. Stuckey, 40, of 3643 Sixth St. SE; Carl L. Cathey, 36, of 910 Almer Rd., Oxon Hill; Irene M. Taylor, 42, of 2300 Good Hope Rd. SE, and Clarence Salmon Jr., 27, of 3607 25th Ave., Hillcrest Heights.

According to sources, the drug smuggling empire had been built from the remnants of once-prosperous drug organizations here that had fallen apart as their leaders were arrested.

Drug agents said the alleged Gray ring was unprecedented in the amount of heroin it had consistently been able to bring into the country.

Integral to success of the operation, according to sources, was the force of Gray's personality. A man with an iron gaze who is both self-assured and, sources said, rughless, Gray strikes fear in those who deal with him.

Gray grew up in Southease Washington and has been known for years as a police fighter, a man who enjoyed taunting police officers, according to sources. In the 1960s he weighed between 250 and 300 pounds and earned the nickname "Big-Boy" and "Bruiser," from policemen who tangled with him.

He was convicted in the 1960s of carrying a dangerous weapon, bank robbery, forgery and petty larceny, and escapes jail on those charges by pleading insanity.

After receiving an indeterminate commitment to St. Elizatbeths Hospital, Gray, in a letter that was later place in his court file, boasted to a friend that "you know and I know I'm not a sick man."

A St. Elizabeths psychiatrist, who observed that Gray's behavior changed markedly after some outstanding charges against him were dropped, charged in court that Gray had duped doctors and demanded his release from the institution, but a federal judge in 1970 ordered Gray kept there. He spent six years in St. Elizabeths, gaining release in 1974.

At various times during his commitment, Gray told docctors he was Al Capone reincarnated and the head of the Mafia, according to court papers.

He grew up stealing from drugstores and never stopped, according to testimony in court papers. In 1967 after he beat up a probation officer in U.S. District Court, Judge Burnita Shelton Matthews told Gray's defense attorney, "I think he (Gray) is just an outlaw and will continue to be one."

In testimony at bond hearings yesterday, prosecutors portrayed the Gray organization as one that would not hesitate to kill anyone. Prosecutors said that two couriers working for the organization had been killed and a third seriously wounded because they were suspected of cooperating with law enforcement officials.

Authorities pursuing the shooting of prosecutor Leibowitz have charged in an arrest warrant that Robert Earllyons, a Northwest Washington man, was the gunman, and U.S. Attorney Silbert said yesterday authorities believe the shooting was linked to the ring.

If so, "it was the worst thing they could have done to themselves," according to one prosecutor. "It just intensified our effort."

Other prosecutors have been brought in and Leibowitz, only slightly wounded, remained on the case. Leibowitz appeared in court both in Prince George's County and in the District of Columbia yesterday to present evidence at bail hearings against Gray and the other defendants.

Arrests in connection with the case began in December in Europe when Dutch police, working in cooperation with American authorities, arrested in Holland Elfriede Helena Anna Visser, a Dutch citizen who the government charges was involved in the drug ring.

According to the government's affidavit, Visser "confessed to her drug-related travels." Then, last week, according to the affidavit, Dutch police also arrested in Holland Fehim Dincer, a Turkish national, who allegedly had more than one pound of heroin in his possession when arrested. Dutch police also arrested another Turk, Tahir H. Engin, also allegedly involved in the drug traffic.

Authorities substituted an undercover agent who made contact with the two alleged couriers for Gray when they arrived in Amsterdam a few days ago, according to the affidavit. The alleged couriers, Ernest Fletcher and Smith Darnell Hammone, got from the agent packages of white powder into which a small quantity of heroin had been put according to informed sources. The two couriers, kept under constant surveillance by federal authorities, flew back to the United States with a powder in plastic packages taped to their bodies.

After arriving back in Washington, the two couriers went to the late night rendezvous with Gray in Oxon Hill where Hammond was arrested, according to court records. The other courier, Fletcher, was covertly assisting government investigators, according to the affidavit.

The taping of the heroin ot the couriers' bodies modified an earlier, more complicated method of transport used by the drug ring, according to the government's affidavit.

Initially, the government stated in its affidavit, couriers would stop in Copenhagen, purchase Marlboro cigarette cartons at the duty-free shop at the Copenhagen Airport and carry the cigarette cartons to Amsterdam. In Amstedam, the cigarette cartons would be "meticalously opened and the cigarette removed" with the reroin being substituted.

Couriers were instructed, the affidavit states, to change their return destination from New York to Chicago and to purchase Marlboro cigarette cartons from the buty-free shop at the Amsterdam airport. Because of the design of the duty-free bag provided at the Amsterdam airport, the cartons, "with some manipulation," cout be slipped out of the duty-free bag and the disguised heroin slipped in without breaking the seal on it. In that manner, the affidavit states, couriers arrived in Chicago with duty-free cigarettes in a duty-free bag "with a seal sffixed showing that the bag had never been opened from the time it was purchased in Amsterdam until its arrival in Chicago."

In a hearing before U.S. Magistrate Henry H. Kennedy Jr. yesterday afternoon, surety bonf of $150,000 was set for Gray, $125,000 for Stuckey, $100,000 for Wilson and Nelson, $75,000 for Smith, $50,000 for Cathey and Taylor and $25,000 for Salmon.

During an unusually stormy hearing, Kenneth Robinson, appearing as an attorney for both Gray and Wilson, characterized the government's affidavit in support of their arrest warrants as "60 pages of puffery." Leibowitz, in response, accused Robinson of "making up facts" while arguing for lower or no bond for his clients. Leibowitz had sought bond of $1 million for Gray and $750,000 for Wilson, Stuckey and Smith.

In Smith's case, Leibowitz warned that if Smith were released, "he's going to be killed." Leibowitz said that the government's experience "with this organization is that couriers who appear to be cooperating with the government are killed."

Gray and four other defendants, Hammond, Salmon, Cathey and Wilson, originally were brought before U.S. Magistrate George E. Burgess in Hyattsville yesterday morning to have bond set. The five waived their right to an extradition hearing, however, and were brought to the U.S. District Courthouse in Washington in the early afternoon.

Two other defendants, Greer and Fleming, were brought before Burgess, who set bond at $150,000 for Greer and $250,000 for Fleming. They were being held in a federal holding area in the Prince George's County jail. A hearing was set for today before Burgess to determine whether the two women wish to waive their right to an extradition hearing before being brought to the District of Columbia.