Just thinking out loud:
- on how a LE investigation might proceed
- on the necessity of mixing coins
As follows:
LE takes down a marketplace, acquires transaction records, and decides to pursue a particular purchaser
Traces the blockchain and discovers coins received via exchange at LBC / Paxful
LBC / Paxful surrenders records of the transaction, which include uploaded images of the bank deposit receipt, which has imprinted the branch number, and timestamp
The bank surrenders DVR imagery of you making the cash deposit.
You receive a knock at the door, and are accused of purchasing bitcoins which were used in an illegal transaction.
You acknowledge buying bitcoins, but deny any knowledge of said illegal transaction. You claim that you may have transfered the coins to another individual (reflected by your transferring the coins from your LBC / Paxful account, to a darknet wallet). You claim you do not know the identity of the individual to whom you transferred the coins, as the exchange was fascilitated via an online forum, such as Reddit. You claim you do not remember any other details.
I suspect that transferring coins from LBC / Paxful to at least 2 different wallets (clearnet => darknet), prior to transferring them into a DNM, creates more than enough reasonable doubt that you were in fact the purchaser in the DNM illegal transaction in question.
EDIT: formatting
ADDENDUM:
EDIT: spelling