NASCAR: Oral-B USA 500-Qualifying

NASCAR Sprint Cup Series driver Tony Stewart during qualifying for the Oral-B USA 500 at Atlanta Motor Speedway. (Kevin Liles / USA Today Sports / August 30, 2014)

NASCAR star Tony Stewart, emerging Friday from three weeks of seclusion after his race car struck and killed a 20-year-old fellow driver, said the incident was "one of the toughest tragedies I've ever had to deal with."

Stewart also said he wanted the family and friends of the driver, Kevin Ward Jr., "to know that every day I'm thinking about them and praying for them" and that their suffering was "something I can't possibly imagine."

Stewart's comments came in a 2 1/2-minute statement he read at a news conference at Atlanta Motor Speedway, where he is returning to NASCAR Sprint Cup racing this weekend after missing three races following the Aug. 9 incident.

He did not take questions, mainly because the office of Ontario County (N.Y.) Sheriff Philip Povero is still investigating the accident. Povero's office said Friday the probe "will continue for at least another two weeks."

"I need to respect the ongoing investigation process," Stewart said.

Stewart has not been charged in connection with the incident that occurred during a sprint-car race at the Canandaigua Motorsports Park dirt track in upstate New York.

Meanwhile, NASCAR ruled that Stewart was eligible for this year's Chase title playoff despite missing three races.

Cup drivers are required to either qualify or race in all 26 of the series' regular-season races to make the 10-race Chase unless NASCAR waives the requirement.

After evaluating "a very unique set of circumstances" surrounding Stewart, "we've come to the conclusion that Tony would be eligible to participate in the Chase if he were to earn a spot," NASCAR President Mike Helton told reporters at Atlanta Motor Speedway.

There are two races left before the Chase: At Atlanta and the following weekend in Richmond, Va.

Under a revised format implemented this year, a win during the season virtually assures a driver a berth in the 16-driver Chase. Stewart, already a three-time Cup champion, does not yet have a win.

If Stewart were to win one of the next two races, he likely would make the Chase.

The fatal incident began when Stewart and Ward were racing side by side and Ward's car crashed into the fence. Ward got out of his car, walked on the track and appeared to be angrily gesturing toward Stewart when he was struck as Stewart's car circled back around.

The story and a graphic amateur video of the race triggered a heated public debate about who might have been at fault.

Before the incident, Stewart, 43, was known for his temperamental, brash personality that included often sparring with the media.

But on Friday, Stewart spoke with a soft voice choked with emotion. Seated in front of a white backdrop devoid of the normal sponsor or speedway logos, he said the incident "will definitely affect my life forever."

Stewart said he stopped racing "out of respect for Kevin and his family and also to cope with the accident in my own way. It's given me the time to think about life and how easy it is to take it for granted."

Stewart said he wanted to get back behind the wheel because it would "help me get through this difficult time."

Stewart also co-owns his team, Stewart-Haas Racing, whose other drivers are Kevin Harvick, Kurt Busch and Danica Patrick.

Brett Frood, Stewart-Haas' executive vice president, said it also was "important for Tony to spend time with the [Ward] family. I do believe that will happen in the appropriate time."

james.peltz@latimes.com

Twitter: @PeltzLATimes