If I write the following sentence does the word "inmate" need to be capitalized? Is it a common noun in this case?

Yesterday, inmate John Doe became aggressive.

I had to think about this one. No, do not write Inmate Joe Doe.
I do not think it's a title like Sergeant Joe Doe or Doctor Joe Doe. It's just a common noun being used as an adjective. That's quite usual. It's like cleaner Joe Doe or policeman Joe Doe.



A bit more on capital letters with proper nouns