Algorithm to find the source of a rumor or epidemic in a network

From the write-up at Phys.org:

A team of EPFL scientists has developed an algorithm that can identify the source of an epidemic or information circulating within a network, a method that could also be used to help with criminal investigations.

and perhaps it can be used to find the source of a bug or a set of bugs or possibly extended to find the source of an observable characteristic in software.

The preprint is available here.