well, when i just cite from your own link where it says:

"Before taking legal action against a foreign national, you should consider whether or not it is likely to be worthwhile.

First of all, it may cost a lot in legal fees as it is questionable whether the defendant will either readily agree to repayment of a debt, or have sufficient money to repay debts. Therefore, you need to ensure that you have sufficient funds to commence proceedings.

Secondly, you need to consider the likelihood of being able to recover the debt from the foreign national. If you do obtain judgment against them and they refuse to comply with it, you can take enforcement action through the courts"

So, good luck and keep us updated! As far as the police thing is concerned, they will simply not do anything at all because there is no "public interest". (If it is true or not does not matter, but they are only interested in million dollar frauds or murder stuff). When you start to explain that someone lost bitcoins, they will tell you to go for a private court case, where you will run into the problems mentioned above.