Strictly speaking, this is OT (because you are seeking a German translation). However, for future reference, I'll mention that one of my friends has an "alias" on his bar admission certificate (to practice law).
His full name (which I won't give here) is John Paul Ringo, but he always went by, and was known as, Robert ("Rob") Paul Ringo. The certificate shows "John Paul Ringo, alias Robert Paul Ringo."
He has the certificate hanging on the wall of his office.
The upshot: "alias" is not used by or for criminals only. It simply means what it means--it's not necessarily either positive or negative.*
*That is not to say that I didn't laugh at Rob when I saw his certificate with the "alias" in it.