One afternoon in January of 1998, a prosecutor for the state of Georgia sat in the very back row of seats in a courtroom where a divorce trial was unfolding. The prosecutor was not involved in the divorce case – he handled murder trials. But he had come here today, because he had gotten a very surprising phone call about an unsolved case he had worked on a year and a half earlier. The caller had told him that the testimony in this divorce – could solve that murder. Now, in the courtroom, the prosecutor felt his heart rate pick up, as the witness he had been waiting for took the stand. And as soon as the witness started talking – the prosecutor knew: he had solved the murder.