The Marin County Coroner’s Office has ruled out suicide in the May death of developer Bijan Madjlessi, a central figure in the collapse of Sonoma Valley Bank and the target of federal prosecution at the time of his demise.

Investigators have determined Madjlessi’s death resulted from an accidental vehicle crash and nothing more, Marin County Sheriff’s Lt. Keith Boyd said Wednesday.

“With his history, you know, we definitely evaluated other factors — really took a hard look to make sure that nothing appeared or presented itself to indicate it was a crime, or nothing appeared or indicated it was a suicide,” Boyd said.

But all the evidence, he said, “just led us to, ‘This is an accident.’ ”

Madjlessi, 58, had been arrested four weeks earlier on charges of bank and wire fraud, money laundering, conspiracy and other federal criminal offenses in connection with a complicated series of loans and financial transactions that ultimately led to the failure of Sonoma Valley Bank.

He personally faced 28 criminal counts, including 13 that carried maximum penalties of 30 years in prison and $1 million in fines, according to the U.S. Attorney’s Office.

Conviction also would have exposed Madjlessi to asset forfeiture, which would have permitted the government to seize his home or other assets acquired with the proceeds of criminal conduct. His death means any such assets are no longer at risk of forfeiture, even though three defendants are still charged in the case, according to New York attorney Steven L. Kessler, a national expert on asset forfeiture law.

Madjlessi and his business partners defaulted on at least $34 million in loans made by Sonoma Valley Bank, which was closed by regulators in 2010.

A three-year federal investigation resulted in a 29-count grand jury indictment issued March 19 and unsealed April 9 that charged Madjlessi; his attorney, David Lonich of Santa Rosa; former bank president and chief executive Sean Cutting, a Sonoma resident; and former bank chief loan officer Brian Melland of Santa Rosa.

All four defendants pleaded not guilty, and Madjlessi was “completely convinced” that he would be acquitted of the charges, his defense attorney, Steven M. Bauer, said last May.

Then the morning of May 4, Madjlessi left his nearly 7,000-square-foot estate near Tiburon to drive to Stinson Beach for a walk.

When he missed an afternoon appointment and failed to return home by nightfall, the circumstances of his life provoked a variety of questions about his disappearance, and authorities and family members raised the possibility that Madjlessi might have been under enough stress to take his own life.

Two days later, Madjlessi’s body was found in the wreckage of his gold Mercedes SL550 about 350 feet below Shoreline Highway, approximately 2 miles from the coast and Muir Beach. An autopsy revealed Madjlessi suffered multiple blunt impact injuries, Boyd said. Toxicology tests turned up nothing but caffeine and ibuprofen in his blood, he said.

CHP investigators found no evidence Madjlessi was traveling at speeds beyond the posted 35 mph speed limit when the vehicle left the road, CHP Officer Andrew Barclay said. Madjlessi also was wearing his seatbelt, Barclay said.

The CHP called in special investigators and Mercedes technicians to rule out mechanical defects, Barclay said.

“We didn’t find anything to support that he had suicidal ideation at that time (or) previously,” Boyd said. “... CHP investigation doesn’t reveal anything to indicate that it was an intentional act or criminal act. We determined it’s not criminal at this point. It’s not suicide.”

Bauer, at the time of Madjlessi’s death, said anyone who knew the developer would find the prospect of his suicide “inconceivable.”

“He is not that kind of person,” Bauer said. “He is a strong, committed optimistic person. None of us believe for a second it could be suicide.”

A federal judge dismissed charges against Madjlessi on May 27 because of his death.

The case is pending against Lonich, Cutting and Melland. The latter two have been forbidden to work in the banking industry.