U.S. District Judge Thomas Penfield Jackson recessed D.C. Mayor Marion Barry's trial yesterday because a juror was admitted to a hospital for illness and depression.

Jackson called lawyers for both sides into the courtroom at 2 p.m. to announce that juror Deborah Noel, 34, had been examined by her physician at Providence Hospital and was unable to continue deliberations at least until today. Yesterday, the jury marked the end of its first week of deliberations.

The judge said he had spoken to Noel's physician and was told that although there appeared to be nothing physically wrong with the juror, the doctor said Noel was "deeply depressed."

In a statement, the hospital said yesterday that Noel had been admitted for observation "to monitor her blood sugar."

Noel said in her juror questionnaire that she is a diabetic, but Jackson said yesterday that her doctor found that "there is no indication for any medication."

The development appeared to further complicate the jury's deliberations on the 14-count cocaine possession, conspiracy and perjury indictment against the mayor. Some observers said it could be another sign that the jury is encountering serious problems.

Earlier this week, in an awkward courtroom scene, the jurors announced that they had reached a verdict on one count, and then declined to reveal the decision. At that time, the jury foreman repeatedly asked the judge to poll the jury.

"This is grist for a mistrial," said Washington lawyer W. Gary Kohlman. "Things like this are signs of a trial that is starting to unravel."

In her juror questionnaire, Noel was one of a handful of prospective jurors who said she favored undercover operations and approved of using concealed recording devices.

In a brief court session yesterday, Jackson said Noel first complained before lunch that she was not feeling well.

He said Noel was examined by a courthouse nurse, who found that she had a fever. Noel was taken to Providence Hospital and examined by her private physician, the judge said.

"He {the physician} tells me he can find nothing physically wrong with her," the judge said. "She, nevertheless, is deeply depressed and under great stress, overwrought and unable to continue with deliberations today, in his judgment."

Jackson, in announcing the development, said Noel had told her physician that she "will be able, she believes, and willing to return" today to resume deliberations.

Legal experts said yesterday that if Noel says today she is unable to continue the deliberations, it could create significant problems for Jackson.

Federal court rules allow a jury of fewer than 12 to return a verdict in a criminal case under some circumstances. If both Barry and the prosecutors agree, a jury of 11 or even fewer jurors could decide the case. Without an agreement by both sides, the rules allow Jackson to excuse one juror "for just cause."

In 1987, however, the U.S. Court of Appeals here reversed the convictions of nine members of the Black Hebrews religious sect because the judge dismissed a juror who said he couldn't "go along" with the way the federal racketeering statute was written, and "the way the evidence has been presented." In its ruling, the appeals court said the juror's dismissal violated the defendants' rights because the juror "for whatever reason, was not persuaded that the government had met its evidentiary burden."

The Black Hebrews trial also set local records for the longest trial -- 13 weeks -- and the longest jury deliberations -- eight weeks.

Legal experts said yesterday that Jackson, if he wanted to dismiss Noel, would probably need to conduct a hearing to establish a "just cause" for that.

They also said Jackson could anticipate objections from defense lawyer R. Kenneth Mundy.

"I would strenuously object to dismissing her because she might be leaning toward acquittal," said G. Allen Dale. "Even if she isn't . . . your chances are better hanging a jury with 12 rather than with 11."

Two federal trial judges said in interviews yesterday that, if they were confronted with a juror who did not want to continue because of a stress-related illness, they would dismiss her even without the agreement of the defendant if they determined she could not serve.

One of the judges said he would try to limit the decision to the medical reasons for the juror's inability to continue. The other judge said he would not try to invade the jury's "deliberative process." Lawyers, however, said it might be difficult for Jackson to avoid questions that might lead to discussion of the deliberations.

"It doesn't take too much to read between the lines that {her stress} relates to jury deliberations themselves," said lawyer Kohlman.

Lawyer William D. Pease, a former prosecutor, also said he doubted Jackson would "take the risk of going forward with just 11" without an agreement from both sides.

"It would be different if there had been no indications previously of problems with the jury, but if it's the kind of situation where somebody's getting sick because they are depressed and feeling pressure, it's a whole different ballgame," he said.

In February, a federal appeals court upheld a Florida conviction after a judge dismissed a juror who called in sick with an abscessed tooth.

Typically, said Pease and other lawyers, jury deliberations are getting long when they enter the second week of deliberations. The Barry jury enters its second week today.

In addition, the jury has been sequestered since June 18. A sequestered juror is virtually a captive of the U.S. Marshals Service.

All visits by family members are monitored, as are all telephone calls and other communications. Noel has a husband and 5-year-old son.

Medical experts said yesterday that people with diabetes can have special problems in stressful situations. The hospital said Noel is "an insulin-dependent diabetic."

Dale suggested that if the judge is confronted with a decision about removing a juror, he could ask the jury to return the verdict they said they had reached Tuesday on one count, and then dismiss the jury.

That way, Dale said, the judge has "one count in cement and then can take his chance with the Court of Appeals."

Staff writers Barton Gellman and Tracy Thompson and researcher Ben Iannotta contributed to this report.