File photo of NASCAR Sprint Cup Series driver Tony Stewart speaking with crew members during practice for the Daytona 500 qualifying at Daytona International Speedway

Tony Stewart will not race at an Indiana dirt track this week but is undecided about whether he will compete at the NASCAR Sprint Cup Series race in Michigan. (BRIAN BLANCO, Reuters Photo / August 10, 2014)

There is currently no evidence that NASCAR champion driver Tony Stewart committed a crime when he struck and killed a fellow driver in a weekend race, the Sheriff of Ontario County, New York, said on Monday.

"At this time there are no facts that exist that support any criminal behavior or conduct or any probable cause of a criminal act in this investigation," Sheriff Phil Povero said at a news conference, adding that the investigation into 20-year-old Kevin Ward Jr.'s death was still ongoing.