It’s been almost nine months since a seemingly mild-mannered 20-year-old attempted to assassinate then-Republican presidential nominee Donald Trump at a rally in Butler.

And we still have no good reason why.

Sources told The Post the FBI has obstructed efforts to solve the mystery of why Thomas Matthew Crooks, who left no manifesto, did what he did. It’s left local law enforcement as well as Crooks’ former friends, classmates and teachers frustrated.

Those who may know, Crooks’ parents Matthew and Mary, have refused all interviews and remain in their small, three-bedroom home here, sealed off from the world like hermits. Neighbors say they only leave the house at 3 am to buy groceries.