The previous owner of the $30M ought to create another smart contract that says something to the effect of: if $15M is sent to this wallet, all rights to press charges will be waived. They recoop half the money and the "contract executor" can step above ground with no worries.
"Pressing charges" is mostly TV nonsense. Generally speaking it's the district prosecutor's decision, and if they have evidence to charge someone with theft of $30M, the victim can't thwart that by "refusing to press charges". It's not something that can be meaningfully waived (and it's not something Etherium could enforce, anyways).
Fair point. I do wonder if there is a legal way to say return half as I'd like to be spared the legal battle.