They're reselling graves in Cook County, IL

Re: the press conference this afternoon regarding the Cook County cemetery at which 4 employees are accused of digging up graves, dumping the bodies, and reselling the plots to unsuspecting folks...

How do they know the employees had dug up & dumped the bodies? After all, they are in the Chicago area... the original occupants of those graves may very well have simply decided not to return to their resting places after having voted.