"Once Tony is able to talk, or does talk, I think a lot of us and many people out there will feel better hearing his side of the situation," Johnson, the six-time NASCAR Sprint Cup Series champion, told reporters at Michigan International Speedway.
"I know what I believed happened," Johnson said. "I think it was completely an accident. So, in time we'll see, when Tony is able to talk and how things go from there."
Stewart's car struck and killed driver Kevin Ward Jr., 20, last Saturday night while Ward was on foot during a non-NASCAR, sprint-car race in upstate New York.
Ward climbed from his wrecked car, stepped on the track during an ensuing caution period and appeared to be angrily gesturing toward Stewart when he was struck by Stewart's car as Stewart circled back around.
Funeral services for Ward were held Thursday in Turin, N.Y. Stewart has not been charged with any wrongdoing but an investigation by local law enforcement authorities is ongoing.
Stewart hasn't commented publicly about what happened beyond a statement last weekend saying there "aren't words to describe the sadness I feel about the accident" and that he wouldn't be driving this weekend in the NASCAR race at Michigan International.
Asked if he had talked with Stewart, Johnson said, "I haven't been able to get in contact with him. I've certainly tried. I have not heard back."
Johnson also said he was concerned about "the pain and sorrow that the Ward family and friends are going through. It's such a sad, sad set of circumstances; certainly a hot button for different sides and different reasons and different opinions."
Carl Edwards said no one should make assumptions about the incident.
"I have been around racing my whole life; I don't know what happened," Edwards said. "It's not right for me to discuss what happened because I don't know.
"The thing I do know is that was a tragedy and my thoughts and prayers are with everybody involved."
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