I don't believe this statement is true. He has a single conviction of "possession of a bludgeon." That charge is almost 25 years old, and as some legal scholars argue, bogus: knives and bludgeons are protected under the Heller definition of RKBA [I agree.]
A prior accusation of assault and battery [almost 30 years ago] that amounted to nothing is not part of his "criminal history."
My information was that he was convicted of assault and battery, but if that’s incorrect, thank you for setting it straight.
I disliked the vague and unspecified accusation. “he had some additional prior violent criminal history” If you can’t say what, or don’t know, then you shouldn’t claim it.
It made me want to shoot the author in the back as he was fleeing, defenseless. (/sarc)