There is no evidence left behind that would suggest anything else than the prisoners dying via heart attack, however, the prisons report no unusual activity before the murders or after, the only anomaly being the way of their death. The FBI and CIA contacted you to solve this mystery before the world learnt of such a powerful weapon existing. The truth of case is, Light Yagami, a 17-year old student, earned a notebook which would allow him to kill anyone who's name entered it.