Hank isn't sure he believes this is a serial killer. Despite Agatha's insistence, he knows serial killers aren't as common as she'd like them to be for her research. Maybe deadline enthusiasm is making Agatha see this as more than it is.
But Agatha knows her way around bodies, and the dead Santa's have too much in common not to be connected. Her real-world training as a forensic anthropologist pays off as she matches wits with law enforcement's best, and a deviant killer's worst.