It mentions he had already been a convicted, or at least arrested, for a prior crime. That's why they had his fingerprints on file.

Whether that crime was a felony, I don't know.

But I believe the "felons can't possess firearms" also includes possession while committing a felony - you don't need an actual conviction (but the felony would need to be proved).

That he was previously convicted of felony possession with intent to distribute and that this precluded him from owning firearms is the only felicitous reading of that sentence.

I can't tell from the article.

Certainly if he was previously convicted he can't legally poses a firearm.

However I believe that possession of a firearm while operating a drug distribution business is also illegal.

The article seems ambiguous on which it is.

Felons cannot own guns in the US. There's nothing complicated about it.

It's actually more complicated than that. In many states if you are convicted of a non-violent felony then at the end of your sentence your firearm rights are automatically restored. There are also the cases of pardons, expungements, and other restorations of civil rights. It varies by state, and while USC 922(g) outlaws firearm ownership possession by any felon, in practice the Federal courts look at whether the person has had their civil rights restored in the state of the alleged offense. When it comes to Federal charges, the prospect of amelioration is grim. In the Federal scenario, there is no expungement or pathway to restore your civil rights, but a pardon is possible. [0]

There's also a discussion to be had about your and the legal definition of a "gun." For example, antique firearms such as some black powder rifles are specifically excepted [1] from the Federal legislation, but it could vary on a state by state basis.

[0] https://www.justice.gov/archives/jm/criminal-resource-manual...

[1] https://www.law.cornell.edu/uscode/text/18/921

Well they can, they just aren't allowed to...