Federal prosecutors are scheduled to unveil indictments Thursday following a three-year criminal investigation into the collapse of Sonoma Valley Bank, according to sources familiar with the case.

KTVU Channel 2 reported that Marin County developer Bijan Madjlessi and three others appeared in U.S. District Court on Wednesday afternoon to face charges of bank fraud, wire fraud and money laundering.

The U.S. Attorney's Office did not return phone calls seeking comment Wednesday evening. Sources close to the probe said prosecutors were preparing to announce a series of indictments in the case Thursday morning.

Madjlessi referred questions to his attorney, who could not be reached for comment Wednesday night.

Investigators launched a probe into the relationship between Madjlessi and bank officials after Sonoma Valley Bank imploded in 2010.

KTVU reported federal agents searched a Mill Valley home owned by Madjlessi on Wednesday and removed boxes of evidence.

Madjlessi and his business partners defaulted on at least $34 million in loans from the bank in 2010, according to a series of stories by The Press Democrat in the wake of the bank's failure.

In October, the Federal Deposit Insurance Corp. filed a civil lawsuit against three Sonoma Valley Bank officers, seeking to collect more than $12 million for losses.

The suit contended the bank approved loans to entities affiliated with Madjlessi in disregard of prudent lending practices. It alleged that bank officers knew or should have known they were lending to one borrower in excess of banking or legal limits, that the transactions were based on stale or inadequate appraisals and that the borrowers were debt-laden and had little or no equity invested.

The lawsuit named the bank's president and chief executive officer, Sean Cutting, former CEO and director Mel Switzer and vice president and chief loan officer Brian Melland. None were charged with a crime, but the suit accused them of gross negligence and breach of fiduciary duty for their roles in the institution's failure.

The bank was shuttered in August 2010 and sold to Westamerica Bank. At the time, Sonoma Valley Bank's top leaders, including Cutting and Switzer, issued a public statement blaming the sharp real estate downturn for their troubled loans. They said the bank had been profitable in its most recent quarter and would have returned to financial health.