In browsing around, it appears that the article in the OP is a response by Ingrid Newkirk to an article by Nathan Winograd. People can do their own search but it appears that Mr. Winograd is a credible critic of PETA. He is a lawyer with a background in the SPCA and has written a book titled 'Redemption'. You will get many hits if you google his name to find out more about him. Here is the link I found that connects him and Ms. Newkirk....
Animal Rights - Change.org: PETA's Euthanasia/Killing Record: Ingrid Newkirk Responds