I also think the police won't do anything
Surely! As soon as they need taxes, they are right there, but when looking for stolen cryptocurrencies, they can’t do anything. 
Contact them anyway. Let them work off their salary, which they receive from your taxes.
Which secure BTC Wallet do you recommend for me to hold?
It will not be too easy to answer your question in a nutshell. Better take a look at this section Hardware wallets and read the discussions about various hardware wallets yourself.I heard about 25th words of 100 characters and multi sign.
The 25th word is mentioned in the Trezor’s blog. By the way, you can pay attention to their hardware wallets.I thought about Tails live USB which has electrum in wallet.
Having a hardware wallet will still be a more reliable solution. You can combine "Tails live USB which has electrum in wallet" + hardware wallet.