Boston police discovered $5,000 worth of drugs in a locker in the basement of the B.U. Union, Friday, touching off an investigation of the use of drugs in the city. Campus police will conduct a separate investigation of drugs at B.U.

Police arrested Brian E. Dillon, 20, later that day as he attempted to remove the drugs from the locker. Dillion who is not a student, is being held in $5,000 bail.

A second man is being sought in connection with the drugs, a source at the B.U. News said yesterday.

Dillon is charged with possession of narcotics and will stand trial Jan. 13 in Roxbury. He could receive a maximum sentence of two and one half years imprisonment.

The drugs were found accidentally in a semi-annual locker clearance, which was announced a week in advance. The coin-operated lockers, similar to those in many train stations, are not restricted to B.U. students.

Three pounds of marijuana was siezed, with an unspecified number of pep pills. The Boston police are analyzing the other drugs to determine their exact composition. Some LSD is believed to be among the drugs, the B.U. News source said yesterday.

"Isolated Incident"

"There is no indication that this is anything but an isolated incident," Staton R. Curtis, dean of students, said yesterday.

Curtis said that he does not believe that any B.U. students are involved with the drugs, either as pushers or users. He will not make a definite statement until the investigation by the B.U. police is completed, he said.

Boston police last night refused to discuss the planned city-wide investigation of drugs.

Until this incident, B.U. had rarely been mentioned in all the publicity surrounding the ampus drug-boom. Last year, for example, the only drug incident involved several students smoking marijuana. B.U. officials disposed of the case and the police were not called in.