Meanwhile, the bizarre incident on a dirt race track in upstate New York — captured on a graphic amateur video widely seen on the Internet — has unleashed a torrent of public debate about who might have been at fault in the fatality.
Philip Povero, the sheriff in rural Ontario County, N.Y., that has jurisdiction over the incident, reiterated Monday there were no charges pending against Stewart but that an investigation continued.
"There are no facts at this point that would support probable cause of any criminal behavior," Povero told a news conference, adding that "we are continuing to gather all information."
Povero said an autopsy of Ward revealed that the Lyons Falls, N.Y., driver died of massive blunt trauma to the head even though he was wearing a helmet. He was on foot when he was hit.
Asked whether there was any "bad blood" between Stewart and Ward, Povero replied, "Not that we're aware of." He also said Stewart was "available when necessary for additional interviews" by investigators.
Stewart, 43, was driving in a sprint-car race on a half-mile dirt track, Canandaigua Motorsports Park, in upstate New York when his car collided with Ward's, sending Ward's car into the fence.
The video showed that as the caution flag came out and the cars slowed, Ward climbed from his car and, while standing on the track, appeared to gesture with his right arm toward Stewart. After a couple of other cars went past Ward, he was struck by the right side of Stewart's car.
Sheriff's investigators were at the track to review the scene Monday and were looking into whether various factors might have played a role in the incident, such as the lighting at the track and that Ward was wearing a dark driving suit with white stripes down the side.
As the video of the incident went viral on the Internet, the public reaction was divided into four camps: Those who blamed Ward for standing in harm's way, those who thought Stewart was responsible, those who blamed both drivers and those who urged everyone to stop trying to find blame until the investigation is finished.
Another driver in the race, Cory Sparks, a friend of Ward, said he was a few cars back when Ward was killed.
"The timing was unsafe," Sparks said of Ward's decision to get out of his car, according to Associated Press. "When your adrenaline is going and you're taken out of a race, your emotions flare."
Some thought the video appeared to show Stewart's car fish-tailing from the rear and accelerating toward Ward, but others noted that sprint-car drivers on dirt often use the throttle as much as the steering wheel to turn. Povero said Sunday that there was no evidence of criminal intent on Stewart's part.
"None of us, even after the video, have any idea what happened," columnist Will Leitch wrote on the website Sports on Earth. "There is no way a person can watch this video — any video — and be able to tell precisely what went on."
Even so, the emotional reaction was heated. Jeremie Corcoran, the promoter at Canandaigua Motorsports Park, said in a statement that the track took down its Facebook page early Sunday morning "due to insensitive and hateful comments" about the incident.
As for Stewart's NASCAR career, a lot is riding on whether he decides to race Sunday at Michigan International Speedway.
Stewart already has missed one NASCAR race after pulling out of Sunday's event in Watkins Glen, N.Y., in the aftermath of the fatal incident. He is in 21st place in the driver standings and is in danger of missing NASCAR's Chase for the Cup playoff.
If Stewart misses more NASCAR races, it could mean continuing reduced exposure for his main sponsors, such as Mobil 1 motor oil and the Bass Pro Shops retail chain, which help pay the $20 million or so a year it costs to race his NASCAR car each year.
The decision about whether Stewart races at the two-mile Michigan oval, where he is a former winner, "will be Tony's and he will have as much time as he needs to make that decision," Stewart-Haas spokesman Mike Arning said via email.
"It is still an emotional time for all involved, Tony included," Arning said. "He is grieving and grief doesn't have a timetable."
ExxonMobil spokesman Christian Flathman said via email that "this is ultimately a decision for