A bad-check charge against Marlene L. Ramallo Chalmers, the fourth wife of Washington Redskins owner Jack Kent Cooke, was dismissed yesterday in Fairfax County Circuit Court after federal authorities told the prosecutor she had cooperated in a number of cases against major drug dealers.

Commonwealth's Attorney Robert F. Horan Jr. said his office dropped the grand larceny charge of writing bad checks after he received a call about three weeks ago from Assistant U.S. Attorney Liam O'Grady requesting leniency.

In 1986, Chalmers pleaded guilty to conspiracy to import less than a kilogram of cocaine, according to court records, and other charges related to a Bolivia-to-United States drug-smuggling scheme were dismissed. "They were interested in us giving her a break because she testified and provided information in a number of major drug cases," Horan said. "Restitution had been made and we agreed to drop the charges. In this day and age we spend a lot of effort trying to nail drug dealers and it is a minor felony. Any time someone will give you a major drug distributor, that's important."

Horan said that her two-month-old marriage to Cooke was not an issue. "I would have done the same thing if her husband were on welfare," he said.

Chalmers, 37, was married to Cooke, 77, on May 5 at his estate in Middleburg. They revealed the news at the Virginia Gold Cup race, where Chalmers was wearing a huge square-cut diamond ring and wedding band. The two had been linked in news reports for more than a year.

According to friends, Chalmers used to be best friends with Suzanne Martin Cooke, the billionaire's third wife. That marriage ended in October 1988 in a bitter divorce and child support battle. Suzanne Cooke reportedly filed suit against Chalmers because she said Chalmers failed to repay $5,000 she says she lent Chalmers in 1986 to pay for cosmetic surgery.

Chalmers was arrested April 7, 1988, on a felony charge of writing four bad checks to the Cosmetic Center. The checks totaled $285.78. The fact that the amount was more than $200 made it a felony.

John T. "Til" Hazel Jr., who represented Chalmers yesterday in a brief circuit court hearing, said he had no comment on the case. Hazel, a lawyer and powerful developer in Northern Virginia, rarely represents clients in criminal cases. Chalmers could not be reached for comment.

In a 1988 application for a court-appointed attorney, Chalmers, who was previously married to David Chalmers, a wealthy oil executive in Houston, listed her assets as $8 in cash and $5 in a bank account. She also said she was employed as a part-time instructor at Spa Lady in Alexandria. The request for the court-appointed attorney was denied.

Chalmers was indicted July 18, 1988, by a grand jury on the grand larceny charge. The following day, she did not show up in court as scheduled and Circuit Judge Lewis Hall Griffith issued a bench warrant for her arrest. Her attorney, Juan Chardiet of McLean, also failed to appear.

Horan said he did not know why the case had taken so long to come to court.

According to court records, Chalmers, who was born in Cochabamba, Bolivia, became involved in a drug-smuggling scheme that involved couriers transporting cocaine from La Paz, Bolivia, to Rio de Janeiro to the United States.

Chalmers's role in the scheme, according to the records, was to provide a cover by buying tickets and providing expense money for couriers. The documents say she became a part of the scheme after Ariel Anaya, a man charged in the scheme, asked her for assistance. "Ms. Ramallo had been quarreling with her husband because of his infidelity and had agreed to travel with Mr. Anaya," the records say.

According to the records, Chalmers agreed to cooperate with the U.S. attorney's office in other importation cases. "Ms. Ramallo has testified before the Grand Jury and remains willing to testify at trial against any persons charged by the United States," the record says.

In the 1986 case, Chalmers had been charged with conspiracy to import cocaine, importing cocaine, distribution and possession with intent to distribute cocaine, and travel in foreign commerce from National Airport in aid of racketeering, according to court records. Those charges were dismissed in exchange for the plea to the lesser charge of conspiracy, according to the records. She was sentenced to six months and served about four months in a federal prison in Alderson, W.Va.

Chalmers has two children. She came to the United States in her late teens to live with her mother in 1975. According to court records, Chalmers met Angel Miguens, with whom she lived from 1975 to 1981. Miguens was involved in illegal activity, the document said, and it was through him that Chalmers came in contact with dealers.

Staff writers Robert F. Howe and Patricia Davis contributed to this story.