Maryland House Speaker R. Clayton Mitchell Jr. said yesterday that he has been under investigation by a state prosecutor for about nine months -- a probe described by state law enforcement sources as a "full examination" of Mitchell's personal finances and legislative actions.

Mitchell (D-Kent), 54, the House leader since 1987, said he has fully cooperated with State Prosecutor Stephen Montanarelli and turned over personal financial records and "anything else they've asked for. I've done nothing wrong, and I assume that if they haven't come up with anything in nine months, there's nothing there."

State and federal law enforcement sources also confirmed that some information and documents gathered during the Mitchell inquiry have been shared with the U.S. Attorney's Office in Baltimore as part of its investigation of Prince George's County real estate developer and racetrack owner Mark R. Vogel.

Sources in Montanarelli's office said that the Mitchell probe focuses on specific allegations that the speaker received improper financial benefits while holding public office. "We're looking at everything he has done, the full scope of his financial dealings," the source said.

Mitchell, who has retained a Baltimore lawyer, acknowledged the investigation in response to questions from The Washington Post. He said he has received formal notification from Montanarelli that he has been cleared on at least one allegation of improper conduct. He said he was not informed of the nature of the allegation. Montanarelli declined to comment.

Federal investigators have been examining Vogel's vast real estate dealings since his September arrest on a cocaine possesssion charge. Although the Vogel probe began as a routine drug investigation, sources say it intersected with other inquiries into possible influence-peddling by a circle of prominent political figures, lawyers and developers.

Federal investigators are particularly interested in a 1989 Somerset County real estate sale in which Mitchell, a part-time real estate agent, was paid a $100,000 commission for brokering the sale of waterfront property in the town of Crisfield to Vogel.

The transaction occurred at a time when Vogel, the owner of Rosecroft Raceway in Oxon Hill and Delmarva Downs in Ocean City, Md., had several issues pending before the General Assembly.

Mitchell said he and his son recruited Vogel as a client for the property, believing that the developer would be interested in expanding his holdings onto the Eastern Shore.

Although the Vogel transaction came up during Montanarelli's probe of Mitchell, sources say it is not the principal focus of the investigation.

But the sources said Mitchell has provided financial information, including bank statements and canceled checks, which may be useful to the federal inquiry of Vogel.

Mitchell, a businessman who reactivated his real estate business two years before the Vogel transaction was completed, defended the Vogel sale as a "straight real estate deal" in which he and his son received a standard commission paid by the property's sellers, a group of Crisfield businessmen who retained him as listing agent. Vogel paid $1.7 million for the property.

Vogel also denied any wrongdoing on Mitchell's part. "I didn't pay the commission and no one -- no investigator -- has ever talked to me about it," Vogel said.

Montanarelli's probe of Mitchell, a frequent opponent of legislation that would restrict development on the Eastern Shore and elsewhere, began early this year after newspapers reported Mitchell's involvement with two real estate transactions, the Vogel transaction and Mitchell's 1988 sale of his own property to Washington developer Kingdon Gould for $1.8 million.

The Gould transaction involved the Mitchells' 600-acre family farm in Kent County. Gould plans to build about 200 homes on the site.

Montanarelli also received at least two other complaints about Mitchell, sources said. One involved "a sensitive matter that has not yet been made public and that is under active investigation," according to a source in the office.

Montanarelli also received a complaint that Mitchell exerted improper influence late in the 1990 legislative session to kill a bill that would require developers to replace trees they cut down in areas under heavy development. Developers opposed the measure as too costly.

Mitchell's refusal to bring the bill to a vote brought him under sharp criticism from legislative supporters of the bill, some of whom publicly called for a state investigation of Mitchell's conduct.

Montanarelli examined the allegation, but found no basis for criminal prosecution, state law enforcement sources said.

Mitchell, who was busy yesterday conducting a legislative orientation session for new members, said Montanarelli's long-running investigation has been a source of great stress.

"Walk in my shoes for nine months and see how you like it," he said. "There's nothing wrong. There's absolutely nothing there."

Staff writer Howard Schneider contributed to this report.