Potter began to beg injun Joe to not tell anybody that he had killed the doctor.  Joe told him to calm down and quit crying, and that he would not tell anybody about anything.  Then he told him that they needed to separate, and so Potter went one way while Joe went the other way.  And they didn't bother to clean up the mess they had maid, which consisted of a dead man, and bloody knife, and an open coffin.  The oath that Tom and Huck maid to each other was written in their blood on a piece of paper.