When drug baron Pablo Escobar was killed in 1993, his hacienda near Medellin was ransacked for cash, drugs and money. Left behind though were some of the animals from his private zoo, including four hippos. They have multiplied since then and are now spreading down the Magdalena River. While there have been no deaths so far, it is only a matter of time.

Guest: Joshua Hammer, contributing writer with the Smithsonian Magazine.