Brian, that's why they have Google. Spend a minute and find an answer. Then share it with us.
But prior bad acts don't excuse or condone future bad acts. Asking if it's happened before, with the tacit suggestion that it somehow excuses the problem or allows you to say, "See, Dems do it too", doesn't excuse THIS illegal act. I'll try to point out the same problem with the next Dem POTUS. In the meantime, this was a clear violation of US law. Period.
There are 30,000 gun deaths every year in the US. That doesn't excuse the 30,001st killing.