US police have found "no criminal behaviour" on race driver Tony Stewart's part but will continue their probe into the bizarre incident in which he struck and killed an up-and-coming driver.
Stewart, one of the most popular drivers in America's NASCAR stock car circuit, ploughed into 20-year-old Kevin Ward Jr. during a non-NASCAR race on a dirt track on Saturday night at Canandaigua Motorsports Park.
"At this time there are no facts that exist that support any criminal behaviour or conduct or that any probable cause of a criminal act in this investigation," Ontario County Sheriff spokesman Philip Povero told reporters on Monday.
Povero said they have interviewed Stewart and several others who witnessed the incident and they say Stewart, who was unhurt, has been cooperative.
Povero told reporters they are looking for more video footage of the crash as part of their ongoing investigation.
He said they already have two videos of the incident.
"We are seeking persons outside that are familiar with racing that can help us review and analyse these tapes to hopefully fully understand the crash," he said.
Meanwhile, the 43-year-old American, who missed Sunday's NASCAR Sprint Cup Series race at the Watkins Glen International track, has withdrawn from a second non-NASCAR race Saturday in Plymouth, Indiana.
"We at Plymouth Speedway extend our deepest condolences and prayers to the family of Kevin Ward, Jr. and thoughts and prayers to Tony Stewart and his family. Tony Stewart will NOT be racing at Plymouth Speedway this Saturday," race officials said.
There is no word yet from Stewart's team, Stewart-Haas Racing, on whether Stewart will compete in a NASCAR race at the Michigan International Speedway on Sunday.
Saturday's incident happened near turn two at the halfway point of a 25-lap Lucas Oil Super Sprint Features dirt race.
Kevin Ward, Jr. was killed in the incident at Canandaigua Motorsports Park
Stewart first bumped Ward's car and knocked it out of the race. On his next lap Stewart's vehicle collided with Ward, who had climbed out of his car and was walking down the track pointing his finger in the direction of Stewart.
As the car passed by Ward it appeared to rev and then fishtail, hitting Ward and dragging him along the track for several metres.
An autopsy was performed on the body which showed Ward died of massive blunt force trauma. Ward, of Port Leyden, New York, began competing in Go Kart racing at the age four in 1998. He began sprint car racing in 2010 and won his first career sprint car feature in June 2011.