It might be worth investigating, actually. I'd guarantee that the Striker estate still holds the trademark (after all, he's been in some medium or another for seventy years with few interruptions), but the Golden Age comics were published by Helnit/Holyoke, Harvey, and Dell. None of them have a particularly good track record of maintaining copyrights back then.
However, there's a hidden danger: Any of the comics might be based on episodes from the radio show, and copyright protection for audio is left to the states, rather than the Federal government. For one example, New York State courts have ruled that old audio gets "maximum possible" protection, which means that Bell calling Mr. Watson? Protected until the earliest Federal protection expires in a couple more decades.
So, whether or not the comics are public domain, themselves, it's possible that a state court could find that they're derived from the radio shows, making them unavailable for use, even if they're public domain.
Obvious, right? Right...?