Have to correct you, Calilasseia on the radioactivity of Bismuth. The Bi isotpes 212 and 214 are naturally abundant, as short lived daughters of Uranium decay. Especially Bi-214, together with Pb-214, are the isotopes that deliver the dose to human lungs from indoor radon, so this is not an insignificant question. And the relationship between activity and half life isn't "less publicised", but obvious to anyone working in the area.
Otherwise, yes. Co-60 is nasty and it is very good that the Mexican authorities behaved completely responsibly, and issued a global warning, even though they where able to regain it within days, very close to where it was stolen.
Most interesting is that the source was pulled out of its shield and "tossed" out on a field, very close to where it had been stolen. The question is whether the thieves panicked, or if they originally wanted to steal only the shield. Radiation shields for strong sources are commonly made out of depleted uranium. ...Now what else might a shield of depleted uranium conceal
