A two-month police probe said there was nothing to suggest Aubrey McClendon killed himself.
The shale pioneer died after a one car crash.
“We were unable to find any evidence or information that would lead us to believe it was anything other than a vehicular accident,” said Oklahoma City Police spokesman Capt. Paco Balderrama.
The crash, which saw McClendon drive his Chevy Tahoe into bridge, happened a day after he was indicted for allegedly rigging the price of oil and gas leases.
However, the investigation stopped short of completely ruling out suicide.
“We may never know one-hundred percent what happened,” Capt. Balderrama said.
The medical examiner assigned to the case is still to release a final report on McClendon’s death.