The TV and movie stuntman and a passenger in his Porsche were killed in a car crash on Monday morning (20Jun11) in Pennsylvania - and Ebert wasn't offering much sympathy when he tweeted about the sad news.
He wrote, "Friends don't let jackasses drink and drive," prompting celebrity blogger Perez Hilton and Dunn's Jackass co-star Bam Margera to publicly attack him for being insensitive.
Angry Margera took to his Twitter.com account to call Ebert a "piece of s**t," adding, "Millions of people are crying right now, shut your fat f**king mouth!"
But Ebert isn't apologising and on Tuesday he tweeted, "Perez Hilton's readers agree with me and not with Perez about my tweet on Ryan Dunn. He drank, he drove, 2 people died."
But in a thoughtful gesture, Ebert offered his sympathy to Dunn's "family and friends, and to those of Zachary Hartwell, who also died in the crash" on his Facebook.com page.
He added, "It is tragic to lose a loved one. I also regret that my tweet about the event was considered cruel. It was not intended as cruel. It was intended as true.
"I don't know what happened in this case, and I was probably too quick to tweet. That was unseemly. I do know that nobody has any business driving on a public highway at 110 mph, as some estimated - or fast enough, anyway, to leave a highway and fly through 40 yards of trees before crashing. That is especially true if the driver has had three shots and three beers. Two people were killed. What if the car had crashed into another car?"
Toxicology reports to determine if Dunn was over the limit behind the wheel are expected in four to six weeks.