Hmm wonder if the thieves are dead of radiation poisoning yet after they opened the container...
Won't be long. That stuff is suuuuuper hot. Depends on how close the contact was and for how long, but supposedly the Co was found some distance away, so somebody won't need another haircut by dawn, and it'll be downhill from there.
Assuming it's relatively new, of course. And that somebody spent more than a couple seconds holding it. If it's decades old, there's very little cobalt in there, but somebody is still ending up in a hospital.
There's a lesson here... First, don't steal. Second, lead is used to shield things.
Corollary: Don't crack open a lead capsule after stealing it.
