Who decides about the fee amount for a bitcoin transaction? It's the sender alone, he might have delegated this decision to his wallet or provider. E.g. in BTC transaction 3ba0c9eaf3185898164518cda7e3433d1d2049188d737f2b2a7e188aaeb8b4de someone sent 0.01088549 BTC and paid a 2.66038352 BTC fee.
The standard explanation for this is that it was a senders mistake. But it could be as well money laundering. If the sender is the miner or a person dealing with the miner it could be that this fee close to $100k was paid by intention to convert bitcoin from criminal activity into miners coins which are usually seen as innocent virgin coins.
How to investigate this? If the transaction was not in the mempool of the most nodes or if the transaction wasn't in orphaned blocks at similar time then it's very suspicious that the fee was given to the miner by intention to launder the coins.
The standard explanation for this is that it was a senders mistake. But it could be as well money laundering. If the sender is the miner or a person dealing with the miner it could be that this fee close to $100k was paid by intention to convert bitcoin from criminal activity into miners coins which are usually seen as innocent virgin coins.
How to investigate this? If the transaction was not in the mempool of the most nodes or if the transaction wasn't in orphaned blocks at similar time then it's very suspicious that the fee was given to the miner by intention to launder the coins.