At the edge of Old Town Alexandria, Marco's Cafe on S. Washington Street serves a continental menu in a subdued yet elegant atmosphere that attracts city employes who like to lunch in the privacy of the high-backed booths or meet for a drink after work.

As recently as 1983, the evening crowd at the mirrored bar was a mix of young professionals that included off-duty police officers and Alexandria Sheriff Michael E. Norris.

But late that year, reports began to surface that more than food and drink -- namely, cocaine -- was available at Marco's. The allegations prompted a police investigation that one year later has become the subject of a special grand jury probe.

For the past six weeks, Alexandria's political leadership has been embroiled in the controversy.

As information about the investigation has been revealed, numerous questions have been raised about why it was started, the qualifications of the police officers assigned to it, when it started and why it ended abruptly.

Were the Alexandria police investigating the alleged sale and use of narcotics at Marco's, or were a handful of police officers conducting a secret inquiry into Sheriff Norris' personal life? And why did the investigation intensify after the restaurant changed hands in January 1984, even though sources familiar with the inquiry say the alleged drug activity ceased when the new owners took over?

Much of what is known about the original investigation has come from Charles Cox, a police detective then assigned to the investigation who has since left the force, and from a civilian informant who worked with him.

The focus of the investigation, according to Cox, was to gather evidence of a "major narcotic distribution" network and to determine whether Norris used drugs. No evidence linking Norris to a drug operation or drug use was found during the drug investigation, according to Cox.

Nevertheless, Cox has said, Alexandria Director of Public Safety Charles T. Strobel halted the probe in April l984 without following what the investigator called promising leads.

Strobel has defended his handling of the investigation and said that it never ended.

Norris has denied he used, sold or even saw drugs at the restaurant, and has suggested that the probe may have been instigated, in part, because he has homosexual friends, some of whom were also regular patrons of Marco's.

According to the scenario drawn by Cox, Alexandria patrol officer Philip Adcock received information in October 1983 from a person, whose identity has not been disclosed, that "drugs were dealt openly at Marco's and that Norris was present during the usage of cocaine."

Although Adcock and Cox had no prior experience in narcotics investigations, Lt. Arthur Bratcher, then head of the Special Investigations Division that includes narcotics, assigned them to the inquiry.

The two officers were told by Bratcher to keep the investigation secret, according to Cox. "It was run supersecret. The only people who knew everything were me, Adcock, Bratcher and Strobel," Cox has said.

In a memo written after he left the investigation, Cox said that his inquiry "originated from information" supplied by an ex-employe of Marco's who said she had "observed, what is believed to have been about a kilo of cocaine accompanied by several stacks of $100 bills" at Marco's in l983.

That same ex-employe said recently in an interview that her first contact with Cox and Adcock occurred nearly three months after Cox has said the investigation began and a month after Marco's was taken over by new owners in January 1984.

Several weeks after the employe talked with the two policemen, Cox and Adcock had their first meeting with a civilian informant, who Cox said was needed to help gather information from what he described as the many homosexual patrons of the restaurant.

The informant who worked with Cox and Adcock agreed to be interviewed by The Post on the condition his name not be used. He said he has worked in drug cases with several law enforcement agencies in the area since 1981 and that he still works with Alexandria police.

Bratcher has declined to answer questions about the investigation or the informant.

In March the informant met the two officers in a parking lot of the Washington Masonic monument. "It was like Dick Tracy," he said. "They put a mike on me and gave me $1,000," he said.

The microphone was later used to transmit his conversations at Marco's to Cox and Adcock in a nearby car, where the transmissions were taped.

The informant said he was surprised to be working with officers who were inexperienced in drug investigations. "Adcock had not even seen cocaine before," the informant said.

He said he began to suspect the investigation was targeted on Norris -- and not on an alleged drug dealer at Marco's, as he had been told by Cox and Adcock -- after he exchanged phone numbers and addresses with a man named Keith Price whom he met at Marco's.

"Good, that's the address we're looking for," the informant recalls Adcock telling him.

The informant said he once visited Price where he lived and learned from him that he shared the home with Norris.

The informant said he met Norris in the restaurant several times but never saw him or anyone else in the restaurant use or deal in drugs.

Cox said that in early April the investigation "was kind of a stalemate" but he and Adcock "kept getting pressure from Bratcher that if we were going to make a case [against Norris] they wanted it done."

Cox said Bratcher made it clear that since City Council would soon be voting on the proposed merger of the sheriff's office into Strobel's Department of Public Safety, it was urgent to take some action if that were possible.

The council voted April 24 to merge the two departments.

In late April, Cox said he was told the investigation was over and he was transferred to patrol. The informant also said he was told by Adcock that the probe was over.

Cox said that at the request of Bratcher he wrote a 10-page memo summarizing the investigation and urging that it be continued. Strobel said recently that he had never read Cox's memo.

His memo listed four individuals as friends of the sheriff, one of whom "could furnish valuable information concerning Mike's activities . . . . I feel there is something to the allegations against Mike, that they can and should be pursued . . . . "

When asked whether Norris' private life was a reason for the investigation, Cox said recently that the sheriff's sexual preferences were "never really an issue."

Norris said recently that some people have decided it is "a major problem" that "I have homosexual friends and I've gone out with them." He stopped short of saying this was a reason for the police investigation because "I don't know their motivation."

Both Cox and the informant said in recent interviews that the only comment about Norris and possible drug use that turned up during the investigation was by Walter Love, a former housemate of Norris and a bartender at Marco's, who said in a conversation that was taped that Norris used "speed" at home.

In a recent interview, Love said he does not recall making that statement and that he never saw Norris use drugs at home when he lived in Norris' house for about six months in l983.

Norris said recently that Love was "talking about diet pills that I got from Norfolk once across the counter; things that can be gotten from any 7-Eleven . . . . That's all they're talking about."

The informant said that after his involvement with the probe ended, Bratcher told him the police department was severing all ties with him on "orders from above." A couple of weeks later, according to the informant, he delivered a letter to Strobel with copies for Bratcher and Cox complaining about his severance and urging the investigation be continued.

The next day, according to the informant, Bratcher came to his home and told him that he could resume working with the Alexandria police.

On Dec. 21 the Alexandria Port Packet printed allegations from Cox that the drug investigation was prematurely halted by Strobel after Norris' name turned up on a tape made by an informant.

At a press conference the next day, Strobel said that "Sheriff Norris was not the target of the investigation," which began in "late January or early February l984," but his "name did come up during that investigation." He said the police inquiry had continued to that time.

Strobel said the investigation experienced a "lull" after Cox was taken off the case for being "uncooperative." Cox said he was never reprimanded for being uncooperative.

On Sept. 28, the police department wrote a memo to City Commonwealth's Attorney John E. Kloch asking him to review the evidence relating to Norris and to two drug buys made at a restaurant other than Marco's during the investigation.

Kloch has said he found no evidence of wrongdoing on Norris' part and did not file charges in the two drug buys because police were seeking to "climb up the tree" and to reach the supplier of the drugs.

The ex-employe contacted by Cox and Adcock in February said she believed Norris was investigated "because he has a different life style.

"I remember one night some kids at the bar were talking about drugs and [Norris] said 'Listen, I'm the sheriff. I don't think you should be talking like that in front of me' . . . . Mike never saw it being done."