Why would someone skilled enough at hacking to steal the coins from another skilled hacker be then willing to return them to the rightful owners ?why would he not just keep the coins and be rich instead of a small bounty ?
The major btc thefts are almost all well known exchange owners ,ponzi operators, karpeles ,zhou tong ,trendon shavers ,the mintpal and BFL guys etc ...
identifying them and their families is not the problem ,its what the fuck to do with them if they have been too slippery for the police to do anything........theres probably nothing
legal you could do to them which makes the only option ...........something else

It's obvious that you're knowledge on the matter is limited.
There are different type of hackers, good and bad (white and black). You can often read in the news how someone lost x amount of money, and the person returns all of it. There are such people in the world of hackers too.
Anyone who lost funds due to ponzis', online exchanges, online wallets etc., deserved it.
The Bitcoin police idea has been tried before. It didn't work.
Indeed. The capabilities are quite limited and the authorities are useless.