The D.C. police department under former police chief Maurice T. Turner Jr. failed to fully investigate an allegation in 1984 that Mayor Marion Barry used cocaine, according to a confidential police memo examined this week by The Washington Post.

The memo, written last December by then-Assistant Police Chief Charles E. Samarra, said that an investigation ordered by Turner into allegations of Barry's drug use was never fully completed, and that "if these allegations were made against anyone other than the mayor (an officer, for example), that further investigation would have been initiated."

"It was obvious that either the investigating officials (1) were inept; (2) felt that the case would be assigned for further investigation; or (3) were undoubtedly influenced by the importance of the mayor's office," Samarra wrote in the Dec. 13, 1989, memo to Chief Isaac Fulwood Jr. " . . . If we are to be credible, then we must be fair and consistent."

Turner, the Republican candidate for mayor, denounced the memo as "politics," and questioned why it was "intentionally leaked" nearly a year after it was written and so close to Election Day.

"There was no substance to the {1984 drug} allegations," said Turner, who retired in the summer of 1989 after eight years as police chief. "If the department or Samarra feels differently, then I feel it's incumbent upon them to prove it . . . . That report should have been concluded if they felt it was that significant."

The memo concerned allegations by a Howard University Hospital psychiatrist, Alyce Gullattee, that Barry suffered a cocaine overdose when he was admitted to the hospital in September 1983. Samarra's memo did not mention Turner.

The mayor has denied consistently that he had a cocaine overdose, saying he suffered a flareup of a hiatal hernia.

Barry's 1983 hospital visit became news again last year when WUSA-TV (Channel 9) reported that the police department's Internal Affairs Division failed to pursue the doctor's information aggressively in 1984. The television reports prompted Fulwood to order Internal Affairs to reopen the 1984 probe.

The reopened probe was critical of the 1984 investigation, so Fulwood asked Samarra to review both.

After the WUSA reports, Turner said that in 1984, the Internal Affairs Division was unable to corroborate Gullattee's allegations. Gullattee did not examine Barry at the time of his hospital stay and had no access to his medical records. She had only "second-hand information," Turner said last year. He also has questioned the doctor's credibility.

In his memo last year, Samarra said that the matter should not be laid to rest until Deputy Chief Jimmy L. Wilson, who conducted the 1984 probe as head of Internal Affairs, "provides a formalized statement."

"To do less is to admit that allegations against the mayor or others are handled in a 'different' or 'special' way," Samarra wrote. " . . . I feel that we failed in our mission with regard to this particular case."

Samarra, who is now police chief of Alexandria, said in an interview this week that he was not satisfied by the original investigation of Gullattee's allegations because, among other problems, "at least one critical witness was never interviewed and absolutely should have been."

"I felt the investigation had not been properly conducted," Samarra said. "I feel the only way you can get to the truth in any investigation is to follow up any lead and interview all persons who may have particular information . . . . They should have gone forward and done everything they would have done on any other investigation and they did not do that . . . . If {Turner} had the details on the case, then he should have made sure that all the witnesses were interviewed."

Turner's relationship with Barry when he was police chief has become an issue in the mayoral race. His Democratic opponent, Sharon Pratt Dixon, has said he was too deferential to the mayor, and failed to confront him about the department's needs for more resources.

Fulwood and Barry declined to comment on the memo. Gullattee and her lawyers could not be reached for comment. Last year, she said she had not gone to police with the information, but police officials said she had.

Wilson was out of town yesterday and had no comment, said his administrative assistant, Lt. Lowell K. Duckett. Wilson, who many police officials say has been a close ally of Barry's, is now commander of the 6th District, east of the Anacostia River.

Duckett, head of an organization of black officers and a supporter of the Turner campaign, said the release of the memo is "slimeball, dirty politics."

Last week, Barry was sentenced to six months in prison for his conviction on a cocaine possession charge. In a letter to U.S. District Judge Thomas Penfield Jackson, Barry said he is a recovering drug addict. For years, he had denied taking drugs.

Turner said that in 1984 he was briefed on the matter by Wilson after the Internal Affairs Division completed its investigation, but that he "has no idea who the witnesses were. From what Wilson said, there was no substance to the allegations that Dr. Gullattee made," Turner said this week. "We had hearsay evidence."

The entire affair goes back to Sept. 25, 1983, when a D.C. ambulance crew rushed Barry to Howard University Hospital after he complained of shortness of breath and chest pains. Barry has released hospital records indicating that he had a flareup of a hiatal hernia, which can cause symptoms mimicking a heart attack. But Gullattee told Turner that she believed Barry had overdosed on drugs that night, Turner said.

Samarra said he does not know what happened to the reopened Gullattee investigation after he wrote his memo. Police sources said it was never pursued further because Barry was arrested weeks later in an FBI sting at the Vista Hotel.

Last year, after the WUSA television reports, Turner attacked Gullattee's credibility by referring to her actions in the controversy surrounding the 1980 Washington Post news story about "Jimmy," an 8-year-old heroin addict, who later was found to be a fabrication.

Immediately after the "Jimmy" story was published, city officials launched an intensive search to find the boy, and told reporters at the time that only Gullattee knew the child.

Barry said that he had been told by Gullattee that the child's mother had called her and said she and the child had left home, and were in hiding "because she doesn't want to be arrested or have the child taken away from her."

After it was discovered that the Post story was untrue, Gullattee was quoted as expressing doubts about the story.