An Allegheny County Common Pleas judge whose Florida property deals are under federal investigation sued his former business partner yesterday for allegedly conspiring with 11 others to bilk him out of his investments in Gulf Coast real estate.

In a suit filed in U.S. District Court in Pittsburgh, Judge Robert P. Horgos said his longtime friend, Alfredo J. Sararo III, and Mr. Sararo's Florida confederates "engaged in a series of ongoing schemes" in which they flipped high-end condos and vacant lots for a profit while leaving Judge Horgos all the poorer.

Among the accusations are that Mr. Sararo used some $500,000 of the judge's money for himself rather than buying property in the judge's name as the two had agreed.

According to the suit, Mr. Sararo and others also preyed on other Pittsburgh-area investors by inflating property values and taking their money. Next, they bought properties at lower prices than they had reported to the investors. They resold those properties to the investors at a significantly higher price.

At least a half-dozen wealthy Western Pennsylvania investors may have been fleeced in some of the deals, according to several sources.

The suit also alleges that Mr. Sararo, in concert with notaries and two lawyers, forged Judge Horgos' name on deeds to transfer property titles to Eric Harrington, the wealthy co-founder of Moniker Online Services in Pompano Beach, Fla. Mr. Harrington is described in the suit as either a friend or relative of Mr. Sararo's.

Mr. Sararo's lawyer, Robert Rosenblatt, said last night that he hadn't seen the suit and couldn't comment.

Mr. Harrington's lawyer, Jeffrey Fridkin, has not returned repeated calls.

For at least a year, FBI and IRS agents in Pittsburgh have been scrutinizing Florida real estate transactions involving Judge Horgos, Senior Allegheny County Common Pleas Judge Gerard M. Bigley and Mr. Sararo, a former Allegheny County probation officer and amateur tennis champion.

The nature of the investigation and its targets remain unclear. The U.S. attorney's office has declined comment on the matter.

Earlier this year, Judge Horgos filed three suits in Florida against Mr. Sararo, Mr. Harrington and others, alleging that Mr. Sararo forged his name on four Florida properties, effectively stripping them from the judge's ownership.

The federal suit filed yesterday levels new, more serious charges of racketeering, conspiracy and fraud.

Since November 2003, Judge Horgos claims in the federal suit, Mr. Sararo and others misstated the judge's income, took money from his Florida bank account, forged his name on documents and used notaries and witnesses to make the transactions appear legitimate.

At least two of the defendants named in the suit have been contacted by federal authorities in Pittsburgh.

Frances Agosto, a Collier County, Fla., notary, said recently that a Pittsburgh FBI agent called her about the investigation involving "that judge." Ms. Agosto would not reveal details of the conversation.

Pamela Stewart, a Naples, Fla., lawyer and notary who prepared and signed several of the property documents, has flown to Pittsburgh to meet with federal authorities at least once. She could not be reached for comment.

Also named in the suit are another lawyer and notary, John G. Vega, notary Wendy Johnson and several others the judge says witnessed the transactions.

The other defendants are Mr. Harrington; Mr. Sararo's ex-wife, Alana Sararo; Sararo Holdings LLC, a company controlled by Mr. Sararo; and Fifth Third Bank in Naples, where the judge maintained an account.

According to the suit, Mr. Sararo and a purported Fifth Third Bank executive persuaded the judge to refinance his $348,000 Sewickley Hills home and take out a line of credit so he could profit from Florida's booming real estate market. Judge Horgos used the $470,000 in proceeds to open his Fifth Third account to finance the real estate purchases.

The judge accused the bank of sending his financial statements directly to Mr. Sararo without his knowledge.

Judge Horgos, 59, and Mr. Sararo, 38, have known each other for 20 years. Mr. Sararo was an adult probation officer in Allegheny County from 1997 to 1999. He moved to Florida in 2000, but before he relocated, he and Judge Horgos bought a pizza franchise together in Morgantown, W.Va. They no longer own it.

Judge Horgos' Florida adventures began in 2001 when Mr. Sararo showed him property in Naples and encouraged him to invest.

His first purchase: a luxury condominium in The Dunes of Naples II for $350,000. Mr. Sararo lives in the same complex of seven buildings.