By Heide Brandes

OKLAHOMA CITY (Reuters) - The fiery crash that killed U.S. oilman Aubrey McClendon in March after his car hit a wall was an accident, Oklahoma's medical examiner said on Wednesday, echoing a police inquiry's findings a day earlier that there was no evidence of suicide.

The examiner said he died of "multiple blunt force trauma" and his corpse suffered "extensive thermal burns and charring" after his Chevy Tahoe slammed into a concrete bridge abutment on March 2.

The crash happened a day after federal prosecutors indicted him for violating anti-trust laws by rigging bids for oil lands.

McClendon, a pioneer of the U.S. fracking boom who failed to show up at a dinner with friends the night of the indictment, denied the charges.

Toxicology tests showed there was no alcohol in his blood at the time of the accident.

The report said doxylamine, an antihistamine that causes drowsiness and can be used as a sleep aid, was detected but not confirmed in his liver.

The force of the crash fractured his ribs, bones in his arms and legs, and his pelvis, causing acute hemorrhaging, the report said.

Details of the crash, in which his vehicle was driving well above the speed limit at 88 miles per hour (142 kph), stunned the U.S. energy industry.

Many executives worried McClendon, who was ousted in 2013 as CEO of Chesapeake Energy <CHK.N> after a shareholder revolt, had committed suicide.

On Tuesday, Oklahoma City police said they found no emails or notes to suggest he was contemplating ending his life, but acknowledged his state of mind at the time of the crash was unknowable.

(Reporting By Heide Brandes; Editing by David Gregorio and Alan Crosby)