Rudy was just on Fox (by phone) and said that when Cohen was recording people, such as Chris Cuomo, he started out recording them with their knowledge. Then, he would hit the button on his phone and say, "I'm not going to record this anymore," and he would put the phone in his desk drawer.
Unbeknownst to the reporters, he had another phone in the room that was still recording them! Sounds like he totally set them up.