I guess it's always possible to use something like this for money laundering.
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(3) Claim you mistakenly sent the funds and that they're gone, since it's an address whose private key is known.
That's not money laundering. It sounds more like "a boating accident".
Then mix and be happy. Just an idea.
Now you have money you don't officially have, and can't officially spend. Great for buying drugs, terrible for buying a car.