Investigating the Gulf Coast dolphin murders

Along the Gulf Coast, people are killing (and sometime gruesomely mutilating) dolphins in record numbers. At National Geographic, Rena Silverman goes in-depth on the killings, which investigators now believe are the work of multiple people who are not connected to one another. Xeni wrote about it last year, when that was apparently less clear. Is it less or more disturbing that this isn't likely to be an isolated dolphin serial killer?