Graydon Ostler was an award winning chef who came to Portland to set up a fine dinning resturant, the Raven and the Rose. However he, along with his cooking staff were all Bauerschwein, and following the deaths of multiple members of his family, he started murdering Blutbad's that came into his restuarant.
Using a special mushroom imported from the Black Forest in Germany, he made a truffel special and gave it to everyone as compliments of the chef, however due to the nature of the mushroom it would mean that any Blutbad who ate it, would die with agonsing stomach pain, before the stomach's literally exploaded. Using this he indirectly murdered Sam Leoni and Angelina Robinson. Tracing the link Nick and Hank went to his resturant, only to chance the chef shouting at his staff, in that moment they all revealed there true natures. Nick and Hank then talked to him, Ostler denied any knowledge and claimed it was impossible. However later after going through Rosalee's books they found the Mushroom which he was using, and realised how he was poisioning others. Armed with this knowledge Nick confronted him, initially scared when he discovered Nick was a Grimm, Ostler quickly realised Nick didn't intend to kill him, and argued there was nothing Nick could do, as he could never prove it was him. He also went on to point out how Blutbaden had murdered most of his family, and his staff's family, he was just finally starting to fight back. Faced with few other options Nick left, however with Hank and Monroe he formulated a plan, Monroe and several of his other Blutbad friends chased Ostler, but Nick and Hank confronted Monroe, a staged fight broke out where Nick seemed to kill Monroe, then they forced Ostler to agree to confess or they would leave him for the others to rip appart. Ostler finally agreed, so they took him away, back at the precicint he finished signing a signed confession, and asked Nick if he really thought this would stop the feud, Nick admitted it wouldn't, but said "it was a start." Ostler went to jail.