Good posts.

Sollozzo smelled a rat because he was a true gangster. He oozed suspicion and deceit.

As far as getting evidence from the car, it's not likely that Sollozzo's people would want to help the police. Not only would that be bad form for a mafiosi but how do you explain the meeting to the DA- "Sure we went there to discuss narcotics deals, murder and political corruption but forget about all of that-let's find that maniac Michael.."

It's certainly possible that an honest or enraged detective would have done everything he could have done to find the mystery gunman who murdered a police captain.

But resources were limited by modern standards, right? And I believe the FBI would have had the best of what forensic science was available, not the NYPD.

So absent leaving a signed confession or being caught with the gun Michael didn't have too much to worry about. The combination of a good plan, corrupt and greedy cops, along with judicious publicity wielded by Tom's contacts sullying McCluskey's name made Michael quite safe, absent the sort of "accidents" Vito mentioned in his speech.

Speaking of the novel, there is a passage therein where Michael virtually boasts to Kay that although he might end up dead, there's no way he's ever winding up in prison.