Documents in the hands of a federal grand jury in Baltimore reveal a cozy relationship between Wall Street and certain officials of the Food and Drug Administration, a relationship that the grand jury could decide amounts to insider trading.

We reported last month that the grand jury was investigating whether stock brokers and investment counselors were getting advance information from the FDA about drug approvals. Now our associate Jim Lynch has learned what kind of clues the grand jury is working with.Federal investigators found evidence of possible collusion between the FDA and Wall Street in messages carelessly left in the FDA's computers, and even in one FDA trash can.

Thirteen FDA officials and five private individuals were subpoenaed to testify before the grand jury in late March. At least one of the federal employees under investigation works in the FDA's Center for Drug Evaluation and Research.

Some stock analysts and FDA officials say the investigation will fall flat and that it is simply a witch hunt on the heels of the FDA's generic drug scandal in which FDA chemists were convicted of taking bribes from drug companies. But other high-level federal health officials say that while much of the evidence is circumstantial, there is strong evidence against at least two FDA officials.

The joint investigation by the Securities and Exchange Commission and the Health and Human Services Department inspector general has not been limited to one or two leaks from the FDA. It is focusing on a pattern of communications between key FDA officials and investment houses.

Some evidence of the communications allegedly was found by the SEC in the offices of brokerage houses. Other evidence apparently surfaced in the FDA's own electronic mail system that sends computer messages from one office to another.

And, as with the generic drug investigation, some of the evidence was found using good old-fashioned detective work - going through the trash of an FDA employee. FDA officials are being grilled by the grand jury on whether they had any contact with 10 private firms. Three of them are under the same roof in Palo Alto, Calif. Stockbuster Partners and Stockbridge Partners Inc. are limited partnerships under Feshbach Brothers. In stock market parlance, Feshbach is the nation's largest "short seller" specializing in selling stocks right before they drop in value and then buying them back at a cheaper price. Short sellers can anticipate when a company will get bad news, but using confidential inside information about that bad news is illegal. Joseph Feshbach, a partner in the firm, told us, "We're quite confident we haven't been involved in any wrongdoing." And he said no one at the company had been contacted by federal investigators. A stock analyst told us that Feshbach, because of its size, is often the target of allegations by companies that think shortselling damages their stock.

An FDA spokesman told us that agency staffers are run through ethics seminars and told not to comment on any pending drug applications.