The man who led the U.S. government's investigation of Michael Vick's dogfighting case said that he's withholding judgment on the quarterback's rehabilitation. "Do I think he's changed? I don't know," said retired U.S. Department of Agriculture senior special agent Jim Knorr, speaking to ESPN's Outside The Lines. "I would hope he has but I don't know. Only one person knows and that's him. "The only way the public is going to know if he's sincere is to revisit it five to eight years from now, when he's not playing in the NFL and getting endorsements," Knorr said. "Is he still going into the neighborhoods, preaching to the kids? "If he's sincere or not, it doesn't really matter because what he's doing now, he's doing a positive thing by speaking to kids in the community about his mistakes and telling them not to go there. What he's doing is good for the public."