From Sarah Brady’s interview on Booknotes:

“Scott was a little boy about 5. We went to go swimming with some friends, and they had the pickup truck from her business, and the gentleman who worked for her was driving. And Scott hopped in and I hopped in to the pickup truck, and Scott picked up off the seat what we both thought was a toy gun, and he sort of started in to play with it. And I said, ‘Scott.’ And I took it from him. I said, ‘You don't even point a toy gun at anyone.’ And then I realized it was not a toy gun, it was a fully loaded little .22, very much like the one that had shot Jim.“