Vampire Secrets

The video rather interested me, though I could only ever catch about 60% of it.
As a result, I am unsure of the validity of my researching the Vampire of Hanover, but I feel that he bears mentioning.
The Vampire of Hanover was really Fritz Haarmann, resident of Hanover, Germany, employed as a butcher, born in 1879, died in 1925. He was an active serial killer from 1919 to 1924, and during those years killed at least 24-27 young boys, mostly vagrants. He became known as a "vampire killer" because of his disturbing habit of ripping out the throats of these victims with his teeth while sodomizing them. The sodomy presumably had less to do with it than did the throat-ripping.
Haarmann had a boyfriend, Hans Grans, who often purportedly chose the next victim, often purely because he liked the clothes the boy was wearing or thought him particularly handsome. He sold the clothes to secondhand shops, while Haarmann butchered the bodies of the victims like meat animals. He became well-known for always having nice, cheap cuts of meat for housewives.
Haarmann disposed of the skeletal and otherwise unusable remains in the river Leine, his ultimate undoing, for it eventually drew suspicion onto him, as did his constant supply of cheap, good meat. While investigating, police found clothing which matched the description of those worn by the most recent young male disappearance, along with other grisly evidence.
Ironically, Haarmann was a well-known police informant who often gave up criminals to investigators. He was convicted of 24 homicides, and beheaded by guillotine. Grans was convicted of inticement to murder in only 1 of the 24 cases, and originally sentenced to death, but was later retried with new evidence and sentenced to only 12 years in prison. He continued living in Hanover until his death in 1980.
Fritz Haarman's head was preserved for brain study purposes, and is now kept at a well-known German medical school.
Related cases are that of cannibal Karl Grossman, and child killer Peter Kürten, both of whom displayed an inordinate fondness for the taste of human flesh. And were German.
Haarmann, Grossman, and Kürten were all mentioned or referenced in the incredible Fritz Lang film "M".