I was reading about Cashaa, that was hacked and 336BTC were stolen. But the hacker can't move them right? He will leave footprints. So why should hackers steal them since they can be found? For example if they want to convert them to fiat.
The only way I think you could get by from this felony is to keep them on very long term. So long that it may be forgotten. But still, it may.
a hacker of course has an efficient way to get rid of traces so that his Bitcoin can be converted into fiat, maybe one of the things he can do is to divide the bitcoin he gets by confirming it into several altcoins, the rest may be stored for a long time in some different wallet