I never claim to be an expert, but I've read quite a bit about it lately. My understanding is that the pic is copyrighted as soon as it's put in tangible form (registering just allows you a better case and a much higher set of damages if you are infringed upon). I know this wasn't the law in 1930, but I'm pretty sure in this case it would be retroactive. Copyright last for 70yrs past the authors death.
But in either case, you do not own the copyright. He sold you prints, not rights, unless you have a specific contract in writing saying he transfers rights.
I had a thought...can I take my photos that are public domain and improve(colorize,edit),and have any copyright?
No, infact many photographers make this mistake. Did you know that if you took a pic of a billboard and sold the pic, you would be infringing on the copyright of the billboard. Same with statues and other art mediums. So it's a sticky situation. Sure you'd be the owner of the changes you make, but to do that you have to have infringed on someone else's rights. So, as is, right now, you have no rights whatsoever on this subject. If it's in the public domain you can use it but not copyright it.
Now that that's outta the way, let's look at the situation as it presents itself. The guy is dead and you have the negatives. That puts you in a very good position. You may not own the rights to those photos (as far as usage) but you do own the only known negatives. A very powerful position. I'd say you are pretty much free to use them because their isn't anyone to contest it. Anyone else could use them too, but their quality will not match yours and they probably won't bother.