It's a common trope in movies that after someone performs a felony (even murder), if one "lays low for awhile" the case will more or less fade away.
Putting aside the obvious advantage that witnesses' memories fade and eventually they die, does it (still) make much sense that one can avoid being picked up for questioning just by the passage of time? What may have been true in the period depicted in The Godfather doesn't seem like it would apply in this day of database queries during traffic stops and computerized records.
Towards an answer: I assume that if a felony is not solved quickly, it's unlikely to be solved at all, but perhaps there are statistics that show that this is less true than it used to be? Or perhaps statistics about "routine traffic stops" leading to more serious prosecutions?