Mary Beth Sweetland is HSUS's director of investigations. Prior to HSUS, she was the director of research and investigations at Defense of Animals and before that was the director of research and rescue at People for the Ethical Treatment of Animals (PETA).
Sweetland is best known as the PETA executive who vigorously campaigned against medical research with animals even though she is a diabetic whose health relies on injecting herself with insulin that has been tested on animals. In the May 1992 newsletter published by the Southwest Association for Education in Biomedical Research (SwAEBR), she admitted that there was an inherent contradiction in her situation: "[My medicine] still contains some animal products — and I have no qualms about it…. I don’t see myself as a hypocrite. I need my life to fight for the rights of animals.”
In response, Sweetland was the subject of an episode of Penn & Teller: Bulls***, which aired during the show's second season in 2004. Penn Jillette, the show's co-host, told MTV: "I said to the researchers, 'Don't tell me the second-in-command of PETA [Senior Vice President MaryBeth Sweetland] is a diabetic who uses animal products [in the insulin she takes] to keep her alive, but thinks other diabetics should die, because since she's working for animals, it's for the greater good."
Sweetland was also the source of a story on PETA's website that claimed pet-food manufacturer Iams euthanized beagles after conducting tests on them. Iams demanded (and was granted) a retraction after proving the entire story was fabricated.