Stewart spoke publicly for the first time Friday since Kevin Ward was killed earlier this month at a track in upstate New York.
"This has been one of the toughest tragedies I've ever had to with, both professionally and personally," a visibly shaken Stewart said, "and this is something that will definitely affect my life forever."
The sheriff's department in Ontario County, New York is still investigating what led to Ward's death and has yet to rule out criminal charges against the three-time NASCAR champion.
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