A Miami Beach developer and one-time government informant has been indicted on charges that he collected $20 million from fraudulent mortgages on his Miami Beach properties.

A federal grand jury last week charged developer Michael Stern with using the identity of two business partners to buy property on Collins Avenue in their name and then take out mortgages on the property without their knowledge, keeping the money for himself, according to the indictment. Stern, 52, faces four counts of conspiracy, mail fraud and identity theft.

Stern is already in jail in California, after a previous arrest on charges that he helped swindle linebacker Dwight Freeney of the Indianapolis Colts in a bogus restaurant investment deal.

Five years ago, Stern was working with Miami-Dade prosecutors — as a confidential informant in a Miami Beach City Hall bribery probe. Stern said he paid off building officials and planners with more than $100,000 in gifts, and he wore hidden microphones and video cameras to catch them on tape. Three Miami Beach building officials were convicted in the investigation.

But while working as an informant, Stern also was wracking up seven-figure mortgages on many of his properties — mortgages based on false information or forged signatures, federal prosecutors say.

The allegations are not new. Stern has faced lawsuits from at least a half-dozen former business partners and contractors who accused him of forging documents and bouncing checks, court records show.

In the latest indictment, Stern is accused of using the identities of Miami Beach developer Rita Starr and her brother, Steven, without their knowledge. Stern used an unnamed co-conspirator to pose as Steven Starr at a real-estate closing, and he forged Rita Starr’s signature to closing documents to obtain a loan on the property.

Rita Starr and another business partner, Ivor Rose, filed a lawsuit in 2009 accusing Stern of forging loan documents to secretly collect a $4.2 million mortgage without their knowledge.

An attorney for Rita Starr declined to comment on the indictment Tuesday.

Prosecutors say Stern collected $20 million from his schemes, money that prosecutors are seeking to recover.

But getting any money out of Stern could prove difficult. In 2009, he filed for bankruptcy protection, claiming more than $52 million in debts, and a bankruptcy trustee has already disposed of many of his assets.

Earlier this year, Stern and a girlfriend were arrested on charges of siphoning more than $2 million from Freeney by setting up a fake restaurant investment deal. As part of the scheme, prosecutors say, Stern masqueraded as a wealthy investor, claiming to own a private jet and Caribbean homes, using the alias “Michael Millar.”

Stern was arrested after trying to cash a $50,000 check to Freeney from the Indianapolis Colts at a Miami check-cashing store, court records show. Stern has pleaded not guilty in that case.