Just read through this, and since I'm living in Germany, here's my 2 cents:
stuff like this (especially stabbings that end in death) happens ALL the time here, and very often the reason for a mass assault/stabbing is a very minor one.
Several "refugee" housings have been burned down, for example, because the arsonists did not get their preferred breakfast treat one morning. (many millions of euro damage on each)
It happens also that an innocent passersby on the streets is assaulted, beaten in the face, clubbed, stabbed, you name it, for no other reason than looking white.
Which is not a surprise, as Germany took in millions of aggressive people (and if the law were actually heeded, they'd ALL be counted as illegal criminals) many of who openly state they hate Europeans.
Stealing is a bad crime imo. I'm not at all for being lenient on that one.
But chances are that the victim in this incident would have been stabbed anyway.
I've seen just too many people beaten halfdead and stabbed without any reason (of course, there is a simple, well-known reason, but you are not allowed to say that in Germany, or you are a PHOBE).
There are cities here where the police doesn't dare to go anymore. The only law there is the Sharia.
Be careful how you proceed in the future, unless you want that in Poland too.