The fatal car crash that claimed that life of Aubrey McClendon was likely an accident with nothing from his vehicle or autopsy pointing to a specific cause, Oklahoma City police and the medical examiner’s office reported.

Oklahoma City Police Department Capt. Paco Balderrama said separate accident and homicide investigations into McClendon’s death were conducted and concluded in May.

“Our investigators found no information or evidence which would compel us to believe this was anything other than a vehicular accident,” Balderrama said. “We cannot rule out suicide with 100% certainty but we also could not find any evidence directly pointing to it either.”

McClendon, who helped found Chesapeake Energy Corp. (NYSE: CHK) in 1989, was driving near an overpass in March when his Chevy Tahoe moved left of center across a road and struck an embankment to the west.

The police report will not be made public, Balderrama said.

The Oklahoma City Medical Examiner ruled the crash an accident, according to a report obtained by Hart Energy. The cause of death was described as blunt force trauma cased by the crash.

A toxicology analysis found no evidence of alcohol in McClendon’s system or evidence of carbon monoxide, the report said. Doxylamine was detected n his system but was not confirmed. Doxylamine is an antihistamine used in combination with decongestants and the short-term treatment of insomnia.

Since his death, McClendon’s American Energy Partners (AEP) has started the process of shutting down its Oklahoma City office and has reduced staff.

About half of AEP’s 100 employees were laid off May 18 and the remaining employees will close the company within two to four months.

Darren Barbee can be reached at dbarbee@hartenergy.com.