Sascha is a black male cat of the European Shorthair breed.

Francis met Bluebeard for the first time while discovering Sascha's body into the garden of his new home, this first death (actually the last of a long series) prompted the cat to start investigating.

In the novel Pascal explain into his database how Sascha was very young, having reached sexual maturity just a couple of weeks before his dead, and was deemed as far too young to die.