The most famous Bitcoin address is Genesis Block address 1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa and the second is 1FeexV6bAHb8ybZjqQMjJrcCrHGW9sb6uF , as far as I know this second address private key belongs to Mtgox's hacker and FBI had arrested Russians hackers, are those hackers the private key holders from 1FeexV?
No telling if they are the ones controlling it. Someone could've simply paid them in RUB and asked them to transfer to this address.
Here comes the main question, this address starts with 1Fee, that may suggest that is some kind of fee charged to hackers move or whatever cognitive matter, so based on this prefix 1Fee, is it a vanitygen address?
1FeexV6bAHb8ybZjqQMjJrcCrHGW9sb6uF ---> 1FeexVeXqD9H9wwRz6PPQ1byoTWQxyRnRi
No, it is just a normal Bitcoin address just like any other. They don't pay extra fees to use the address.
Also, vanity addresses are just like any other addresses, except for the special bunch of characters. It might have just been a coincidence with an address they generated, or they might have specifically generated that prefix.