Actually PETA explains itself why it kills animals. Interesting. I've tried to find the Court Case files and they seem to have dissappeared. Last I read/heard Peta does not have a shelter, only a freezer.
Here's a couple of links pertaining to the court case.
http://www.telegraph.co.uk/news/uknews/1540785/Peta-workers-dumped-80-dead-animals-in-skip.html