Three students in Michigan are under investigation for posing as a 35-year-old woman online and trying to blackmail a teacher they tricked into sending them photos. The teacher sent a sexually-explicit photo to the 14 and 15-year-olds without knowing they were not the woman. The students then threatened to send the photo to others, which they did. The Van Buren County Sheriff's Office says it went on for about a week before they were called on Monday.