Also, with the passage of time peoples' allegencies change and 30 years is a long time to keep a secret. Whispers will have surrounded these incidents and I suppose that those together with forensic advances mean that there will be a better chance of catching the murderers..........
If, and it's a pretty big IF, the police are convinced that they know who their man is AND there has been a burial, they will conduct either an exhumation to prove it, or take DNA samples from a close family member................
Contrary to popular belief, the files on murders are NEVER closed unless they are solved !
Just because the chances are slim doesn't mean that there are no chances.................Genette Tate being a very recent/very old (1978) case in point.
If there weren't difficulties then the case would have been solved years ago.............
However, I believe that it ain't over 'til it's over and that all avenues should be exhausted until there is a satisfactory conclusion.