The guilt of Albert DeSalvo, the alleged Boston Stangler, is controversial because his initial confessions showed ignorance of many crime details. Although he would later describe details that only the actual killer could have known, his testimony, according to some observers, could have been based on information provided to him by police. Furthermore, several victims who survived did not believe he was their attacker. In addition, because of the lack of a pattern among the victims—who varied in age and ethnicity—some claim that there were multiple killers.