An Alexandria judge yesterday dismissed the first of 26 drug selling charges that resulted from undercover work by two women, mostly in the city's singles bars.

One of the women, Jancice Mary Picha, 25, declared in an interview following the court action: "I'm sorry for the defendants. I'm sorry for Cathy (her roommate Cathy Martindale, an undercover vice squad officer). I'm sorry about the whole thing. It's been one long hassle."

Picha told a legislative committee investigating Virginia's marijuana laws in September she was recruited by her roommate to solicit drugs, that they smoked marijuana to protect their cover and that they made sexual advances to young men to accomplish drug transactions.

That undercover work of Picha and Martindale, 26, over a nine-month period that began last January led to indictment of 26 persons.

Yesterday Judge Franklin P. Backus dismissed a charge to distribute it against Michael Young, 27, of Alexandria after refusing to admit as evidence the police laboratory analysts of the alleged marijuana. He ruled that the prosecution had failed to prove that the substance was continuously in the possession of police after it was allegedly purchased.

Alexandria police declined to say whether they thought the 25 remaining cases that resulted from the undercover work might be similarly jeopardized.

Both Picha and Martindale had testified that Young supplied them with an ounce of marijuana for $35 on July 31. Martindale said she received the money from a friend of Young.

The women testified, the alleged marijuana was kept in an unlocked bedroom nightstand for two days before being sealed in an "evidence" envelope and turned over to Martindale's superior.

Martindale also testified she had gotten "high" on more than one occasion during the investigation.

Martindale said she denied taking drugs when police gave her a lie detector at the time they hired her.

But she acknowledged on the witness stand yesterday that she had used mescaline, LSD, "speed," marijuana and opium prior to her police employment.

Judge Backus swept aside prosecutor David O'Brien's objections to Martindale's drug background being brought into the case.

But it became clear that the handling of evidence of "chain of custody" was the main issue.

Once the marijuana was turned over to the police department, the court was told, it was sent to a laboratory in Virginia for analysts. However, the chemist who supposedly handled the evidence did not testify yesterday. Backus then refused to admit the results of the analysts as evidence.

Holding up the manila envelope, Backus said, "Somebody opened this in the lab. I don't know who it is."

Picha testified as a defense witness at yesterday's trial and expects to be a defense witness at future trials. She hugged Young following the verdict but avoided her former roommate.

"In the end, it could mean Cathy's job," Picha said outside the courtroom. "I'm not proud of that."