I don't think they "shot the PoW", and I don't even know if they emprisoned them. Feels very weird how the original comment put it (why link the Swiss to the Germans like this?).

But I know that German planes ended up in the Swiss airspace. The Swiss told them to land (like "we will now escort you and you will land on our soil, and if you don't comply we shoot you down"). They refused and got shot down.

But it's very different from shooting a pilot that would be in a state of PoW.