The wife of a retired lawyer who was killed by a mail bomb this week has also died, reports the Tennessean. Marion Setzer, 72, had been listed as seriously injured in Monday's explosion. Meanwhile, police trying to get to the bottom of the bombing may have found a vital clue. Among the debris from the blast—which occurred near the front of Jon and Marion Setzer's rural Tennessee home after he picked up the package from his mailbox 200 yards away—was a note police believe was attached to the bomb. Though they aren't telling what it says, a bomb expert notes police will be looking into revenge as a motive; Setzer, 74, had previously worked on general civil cases, including bankruptcy, before his retirement.
"With a note in there, it very well may be some intentional revenge or something, that the attacker, the bomber, wanted to send them a message," the expert says. "This is a very important piece of evidence, because now you may have handwriting." Officials are also investigating whether the package was delivered by private carrier or commercial delivery, CNN notes, adding that the bomb was so powerful that it blasted through windows and scattered debris inside and outside the home. WZTV notes there's an $8,000 reward for information leading to an arrest. (Read more John Setzer stories.)