Three District of Columbia employes and five other persons have been arrested on drug-related charges stemming from a two-month undercover investigation in which D.C. police confiscated about $13,000 worth of drugs, $3,000 in cash and 17 shotguns, rifles and pistols, investigators reported.

City employes arrested are Gregory Lucas, 29, a counselor at a city drug treatment center; Marlin E. Gardiner, 37, a parole officer for the D.C. Department of Corrections; and Albert T. Malone, 49, a corrections officer at the jail lockup ward at D.C. General Hospital, police said.

Police Sgt. John H. Stitcher said Lucas, who lives at 916 E. Meadows Ct., Oxon Hill, was charged with possession of heroin, Preludin and marijuana with the intent to distribute, carrying a pistol without a license and possession of unregistered ammunition.

Police said they seized $800 worth of heroin, $800 worth of Preludin, a .38-caliber pistol and a small quantity of marijuana when they arrested Lucas Thursday at his job in the drug treatment center at 14th and Q Streets NW.

Gardiner, who lives at 6726 Swarthmore Dr., Alexandria, was charged with carrying a pistol without a license, Stitcher said. Gardiner works as a parole officer at 614 H St. NW, Stitcher said.

Malone, who lives at 4916 Glassmanor Dr., Oxon Hill, was charged with possession of Preludin and marijuana with intent to distribute and carrying a pistol without a license, Stitcher said. Police said they seized a pound of marijuana, more than 100 syringes and more than 100 pills from Malone when he was arrested Wednesday.

Stitcher, who works in the internal affairs division, said five other persons have been arrested on 10 separate drug-related charges. A large quantity of drugs and guns were seized from these five persons. However, Stitcher declined to give their names because the investigation is continuing. s

Stitcher said the confidential investigation began two months ago after a task force of detectives from internal affairs division and the homicide and narcotics squads was set up to investigate drug-related deaths in the area of 9th and O Streets NW.

He said grand juries in D.C. Superior Court and U.S. District Court are investigating the matter. Other arrests are expected, Stitcher said. He added that none of the three city employes has been linked to the deaths.