so I'm reading the W3Foundation docs and I'm wondering about how slashing works in detail on the more technical level.

Let's say for example that the validators have voted and decided that one validator misbehaved and 10% of its stake should be slashed, some of it going to the fisherman and some to the treasury.

In Bitcoin, each transaction has to be signed by the correct key: I write an transaction with some input address, some output address and some amount of coins to transmit. Then I sign the whole thing with the private key belonging to the input address and thus prove that I am the owner of these coins. The miners can easily verify this and will thus consider this transaction to be valid. Without the private key signing the transaction, the coins can never be accessed.

The only way I'm aware of in Bitcoin to effectively remove someone's coins is when the miners blacklist an address (eg when it's known that the coins have been stolen) and thus will not process any transactions including this address. The coins are thus effectively dead/removed.

How does this work in Polkadot? Is there simply a second type of transaction that needs not to be signed, transferring the slashed amount to the new owner (eg treasury or fisherman), and the remaining amount just stays with the old address? Or is it solved via some off-chain solution, i.e transactions from slashed addresses are only valid when the required amount goes to treasury or fisherman? This sounds unlikely, as one might just not use this amount for any transaction for as long as possible. Or do bonded DOT have some other state that has no equivalence in Bitcoin?

Any links to useful videos or Posts are of course welcome