Aww, this makes me kinda sad. No offense to your in-laws but,
almost all GSDs have high prey/toy drive. It's a breed trait. seems like
as soon as the little guy started to loosen up in new surroundings, they
find he's more than they wanted to deal with.

I do hope Sarge finds a younger family that has time to channel his
energy in the right direction. Good luck little buddy.

p.s. On petfinder ad he's listed as Large breed GSD. Will he be full sized
or small?