The sheriff investigating the death of a race car driver in New York state said Monday that while no criminal charges are pending against NASCAR star Tony Stewart "all options" are open and that authorities are seeking any additional video of the incident.

Driver Kevin Ward Jr., 20, was struck and killed by the car driven by Stewart on Saturday night on a dirt track during a low-stakes race at Canandaigua Motorsports Park, about 25 miles (40 km) southeast of Rochester, New York. Stewart, 43, is one of the biggest stars in U.S. auto racing.

Asked whether he expected charges against Stewart, Ontario County Sheriff Philip Povero said in an interview on CNN that he would "not speculate on that at this time" and that "there's much work to be done before we can come to any conclusions."

Some video of the incident has surfaced, but Povero said: "We are basically trying to see if there are any other video recordings that may have been made on Saturday night that could help us in the analysis of this crash."

Asked whether the death was an accident or a deliberate act, Povero said "accurate data from video" would help investigators "clearly isolate what happened."

Stewart's car appeared to have clipped Ward's car and caused it to spin out of the race, video of the incident posted online showed. Ward, of Port Leyden, New York, stepped out of his car and onto the track and seemed to gesture at Stewart before being struck and killed, the video showed.

The sheriff said Stewart, Ward's family, race track officials and management and other race car drivers have been cooperative. Povero said investigators also were awaiting autopsy results. "We have consulted with the district attorney. And although ... there are no criminal charges pending at this time, this is an ongoing investigation and all options remain available, or open, at this time," Povero told CNN. He did not put a timetable on a decision on possible charges.

Stewart, of Columbus, Indiana, is a three-time NASCAR champion and one of the highest-paid drivers. He has occasionally gotten into fights with other drivers, including a shoving match with Joey Logano at the Auto Club 400 NASCAR Sprint Cup race in Fontana, California, last year.

Stewart withdrew from Sunday's NASCAR Sprint Cup Series at Watkins Glen, New York. And he has decided not to compete Saturday in an event at Plymouth [Ind.] Speedway.