Play to Kill: Twin Cities Book 5 by P. J. Tracy
A serial killer is terrifying enough, but when the murder videos begin showing up online - well, then it becomes an issue for computer analyst Grace MacBride and her eccentric crew of geniuses and mavericks. Recruited by the FBI, MacBride, along with Minneapolis cops Leo Magozzi and Gino Rolseth, work together to hunt down the killer. Using sophisticated tracking software, MacBride and her team scour the internet for signs of a possible attack, trying to weed out the staged videos from the real thing in hopes of finding a pattern. But bodies keep turning up, and videos keep being posted, and the team is getting desperate to save lives. It's not until they come across a sinister website that a real lead is discovered. And it takes them all the way to a shocking conclusion . . .