why does jefferson hope want to confess right away

In Part II, Chapter VI, Hope replied that he had many words to speak and did not need to wait until his trial. He said that he would not even be tried, which surprised his captors. Hope asked Watson to put his ear to his chest; the doctor listened and then burst out, "Why...you have an aortic aneurism!" Quite calmly, Hope acknowledged the truth of this, explaining that he got it from years of overexposure and underfeeding in the mountains and that he would no doubt be dead very soon. It was important to him to leave an account of his crimes so the world did not think him merely a "common cut-throat."