Jim is the producer of Tanya's TV show; after you look up her name, go to Channel 11 to meet Jim.
Hint 2
He denies everything except knowing Tanya. But surely he's the "J" who wrote that note we saw in Tanya's apartment. How can we prove he knew Heather as well?
Once you have the client list, use the notes function on Rosa's phone to combine "Jim Peebles" and the client list. Now confront Jim, and he'll spout like a fountain.