>>9157831see
>that don't involve intimidationHave you formally requested him to pay the debt and given a reasonable timeline in which for him to pay it?
You can go write down a summary of the debt owed labeling it as a loan on your paperwork, get it notarized and serve it to him informing him of the deadline.
9/10 this is enough for most people to cave and just pay the debt as lawyers often require a retainer for debt based services.
After that you can hire a formal debt collector regardless of what the money is for it's none of the collectors business as you'd already served him paperwork outlining the debt owed.
The last step is to file with your Amtsgericht after the deadline has passed to use litigation to get at him. Regardless of what the "loan" was spent on since you served him formal paperwork the debt is then legitimate and no matter what he spent the "money" on you still have a right as a creditor to collect the debt in a reasonable manner.
German law is very clear that you as the creditor have all legal rights to enforce the debt up to and including freezing or seizing his assets.
Very often in my line of work we have to deal with people trying not to pay just because they think they're broke. Even if the loan was illegal in their state just days after receiving it we still have the legal right to enforce the contract.
You have to put aside your friendship and take him to court otherwise he's going to run off.
Hope you've learned that loaning people money is no joke especially when you have to get it back.