BALTIMORE, NOV. 19 -- Former Prince George's County police Detective Michael B. Murphy, accused of selling cocaine he seized in police raids, was sentenced yesterday to 10 years' imprisonment by a federal judge after pleading guilty to conspiracy to distribute the illicit drug.

Murphy, 32, a member of the force from 1979 until his resignation a year ago, secretly kept both money and cocaine seized in raids rather than turning them in and putting them "on the books" at police headquarters, according to a prosecutor's statement of facts filed in the case.

He then sold the drugs to various narcotics dealers in Washington and Prince George's County, the statement said. As a result, it said, he spent "in excess of $70,000 more than he received in salary from all known sources" in 1985 and 1986 on personal items, including a car and house.

Murphy, who has been hospitalized for what police called emotional distress, threatened to commit suicide in September 1986, two months before his arrest on the federal drug charges, according to police. In the incident, officials said, he claimed he was wired to explosives and forced the evacuation of the county police station in Bowie. He surrendered and no explosive was found, according to the officials.

In addition to the federal charges, Murphy was indicted last December in Prince George's County on state charges of misconduct in office and stealing $23,000 in jewelry from a Seat Pleasant home during a raid in 1985.

In a nonjury trial before Circuit Judge Vincent J. Femia in June, he was acquitted of the theft charge. Femia took the misconduct charge under advisement and has not yet ruled on it.

Reading the statement of facts in the federal case before U.S. District Judge Norman P. Ramsey yesterday, prosecutor E. Thomas Roberts said Murphy worked with a loose network of drug dealers to sell the cocaine he withheld in police drug raids.

For example, Roberts said, Murphy "met a female in Washington, D.C. . . . . Through that female, Murphy met another individual who he knew was a 'street level' drug dealer."

"Subsequently, Michael Murphy distributed on several occasions quantities of cocaine to that drug dealer in exchange for money," he said.