Case #20180605001: Snorek vs Slark
Snorek claims his other account (Slark) was hacked, not sold
Slark claims he bought the account from original owner, then stake his own btc address on June 10, 2018

assuming current Slark doesn't lie, all this can be avoided if he as a buyer gets all supporting data/credentials
full control of registered email address and any/all btc addresses posted in Slark's posts history
@Slark ask your seller to provide the signed message from one of other posted addresses
if sellers refuses to create signed message, expose his username here to get tagged as account seller/scammer
2014 13qTkApa9UKN4LgdeqEBHCJ7Qdp6FL2UuF Luckyb.it Sig ~ http://archive.is/Ns2U1#selection-2969.0-2969.5
2015 197ZjZEUewwSLozV8JHj5YdKQfRZK1zBNf YABTCL.com Sig ~ http://archive.is/HEhIQ#selection-4619.0-4619.5
2016 196LJBsDHN4TanUqY8pfqABhex4iG4EXJP Rollin.io Sig ~ http://archive.is/5BQ3d#selection-2393.0-2393.5 (found old archive)

@Snorek shouldn't you be able to lock the account when he changes/resets password and/or email address?