Guy who ran over robber 3 times now charged with murder

The robber ran off, but I can understand chasing him. Now running over him not once, not twice, but three times? The first time, you could argue that he was armed with the knife and you were scared and needed to incapacitate him. The second and third times, however is just rage or revenge. Yeah, it's murder. He may get a lienient sentence, but that was murder.