Exactly who was watching Justine and why?
We know Lara had her people watching Justine. That makes sense.
Harry hired Goodman Grey to watch Justine. That makes sense.
People from the Chicago PD and the local FBI office were watching Justine. Why?
Goodman Grey told Harry that Agent Tilly wasn’t involved; as far as he good see, but it was people from the same local FBI office. Could these FBI agents have been doing surveillance for the benefit of the Librarian’s? I imagine these “Men in Black” are small in number and might occasionally need help from other more traditional Federal agencies, but that’s just a guess.
That still doesn’t tell us why the Librarians or any mortal agency would be interested in Justine. Someone would have to have some pretty detailed records about the White Court to want to put surveillance on her or at least know that she was Thomas Raith’s lover and that he was involved in a hit of a major supernatural power.
However, that knowledge could only come from someone well connected within the supernatural community. So not someone like the Alphas or most paraneters, with the exception of Paranoid Gary. It could have come from within any of the major powers, but that doesn’t tell us why someone in the know would share that information with mortals. However, for the sake of argument let’s say someone traded this information with the Librarians. What about the Chicago PD?
My guess is that whoever started the investigation against Harry and Murphy was the same group or person who put Chicago PD personnel to watch Justine, but why? She had nothing to do with the break in at Marcone’s bank. Originally, I thought that whoever was working for the Outsiders was behind Rudolph and his partner, but why would HWWBs put surveillance on itself? This suggests another party is involved. Just a guess, but we haven’t heard anything about the late Wizard Peabody’s partner; the one whose presence Harry felt on Demonreach, since Turn Coat. Whoever was responsible, it doesn't explain how they gained enough influence within the Chicago PD to get the investigation started.
These are just rough guesses. They are not even deeply worked out WAG’s.