delivery time! Slid under the door of his office is an envelope with details on the people he killed. There are names, pictures, and little details like printouts of an older man bugging his daughter on her facebook to make sure she'd done her homework. Things that revealed what kind of people they were and who they were close to. Last in the stack is a crime scene photo of Svetlana's daughters.
Pinned to the whole pile is a note: "They're lying to you because they don't want you to suffer. It's possible to resist mind control."
If Booth asks around he'll find that one of the janitors slid it under his door. A janitor was was later found dead of injuries that seemed to have actually taken case quite a while ago...(aka they were possessed then the demon smoked out)
An envelope is mailed to her with pictures of her daughters. A few shots show them playing on a playground, a couple at school, and one of her walking down the street with them, all three holding hands.
In every picture there is a crosshair trained over their heads.
She also gets a note:
"This is how easy it would be. Don't test me, and don't tell anyone you got this envelope. Computers can be hacked and filters can be broken."