Source: Rule of Fear, pg(s). 2 - 3, 6
The mysterious serial murderer known only as Dr. D has stalked Ustalav since appearing in 4588. In this year, Dr. D first struck in the city of Caliphas, committing five murders in which the victims were completely bisected. In the 123 years since, Dr. D has struck in cities throughout Ustalav, frequently leaving cryptic notes to the authorities with his victims.