Source?

Go look it up

He's twenty, so he could not vote in the last presidential election. He registered just before the primary. That said, registrations don't mean much (sometimes people register to vote against people in primaries). abcnews.go.com/Politics/tru...

Suspect in Trump assassination attempt had registered as Republican but motive unknown

The suspect, Thomas Matthew Crooks, 20, allegedly opened fire on former President Donald Trump before being shot and killed by the U.S. Secret Service.