The good news... It shouldn’t take too long to catch the culprit. Sending snail mail or any other package can be tracked rather quickly... That’s why they caught that ‘would be’ unabomber in Texas so quickly. Video cameras are everywhere so the days of doing pretty much anything in an incognito manner is over... Just ask the Saudi’s... Man walks into embassy... Man doesn’t walk out. Case over.
It depends on which team the FB I agents doing the investigating are on.