 As there was nothing in Canadian forensic literature on bite mark evidence at the time, Swann wrote to the FBI in the United States, hoping for any information on the matter.Swann received a reply from FBI Director J. Edgar Hoover, who directed him to England, where he met a man who had dealt with 20 or 30 cases regarding bite marks.Eventually Swann was able to get the information he needed and based on a cast made of Boden's teeth, he managed to demonstrate 29 points of similarity between the bite marks in Elizabeth Porteous' body and Boden's teeth.