This is all a bit weird.
You investigate a possible grave site. Spends months and years doing so.
Finally find some evidence but cover it back up. Send off soil samples.
The results suggest human DNA or similar.
So you contact the police with the details.
They decide to act on the information.
Now this is the strange bit. Surely you would personally take them to the dig site?
How hard would it be to show them exactly were you dug. There is no way you just randomly dug.
Even if there was several dig sites and you somehow got confused, you would still personally return with the police.
The most worrying bit is the Police had no choice but to take him seriously.
They may have suspected he wasn't credible.
But imagine the media shit show if they refused to follow up his information and later on it turned out to be correct.
He may have wasted Police time and raised peoples hopes just for self promotion.
Either way, he won't be charged.