The old "it takes a dummy to catch a dummy" gambit.
Police then swooped in and made the arrest, as Schindler presumably marveled at his own strength after his plastic prey's appendages went flying in every direction.
While obviously this act made Schindler a prime suspect in the earlier murders, police couldn't prove conclusively that he was the one responsible. So they charged him with carrying a concealed weapon and attempted murder ... of a mannequin. Schindler played his cards wisely, if dubiously, when he claimed that he was aware that it was just a mannequin all along when he decided to pummel it into oblivion. The end result was a plea deal whereby he now faces 8-20 years in prison for attacking a mannequin, but will avoid getting charged with actual murder. On the bright side, at least we'll all be spared the spectacle of a defense attorney trying to argue that he was merely acting on a longstanding grudge against J. Crew displays.