(Sorry if someone else already said this and I missed it), but I agree -- and I think it's the reason LE has been silent about the bullet all this time. I think they believed (correctly) that the killer either wasn't aware he had left it behind, or wasn't aware that ejection marks could be used to match it to his weapon. The only way to keep him from disposing of the gun was for LE to stay mum on the finding of the bullet, until they had a specific weapon with which to compare it.
I do think it's odd, though, that LE couldn't have identified him earlier, by looking for nearby registered gun owners (or ammo purchasers) whose weapons used that type of ammunition, and cross-referencing it with, oh, I don't know, the list of people who were known to be at the bridge that day!?
Doesn't the 2nd Amendment prohibit that kind of analysis in the US? I had thought the government cannot create such databases. According to wiki there is no permit requirement to purchase, or registration of guns.
![en.wikipedia.org](/forums/proxy.php?image=https%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2Ff%2Ffc%2FMap_of_USA_IN.svg%2F1200px-Map_of_USA_IN.svg.png&hash=5ae1190a7fb44a73baa25b157f1a22e7&return_error=1)
Gun laws in Indiana - Wikipedia
But in any event - they could simply ask the people on the list for starters