Ryan is not actually a Grimm. He is a Lebensauger (a Wesen) who suffers from extreme self-loathing. He obsessed over Grimm history to the point of killing his own kind to "prove" he belonged with the Grimms. Key Themes for a Paper/Analysis
The killer is revealed to be Ryan Smulson , the seemingly clumsy and eager police intern. [S2E10] The Hour of Death
The police department is compromised from the inside by an intern who uses his access to stalk and manipulate the lead detectives. Other Possible References Ryan is not actually a Grimm
The episode explores the dark history of Nick's ancestors (the Endezeichen ) and how their legacy of brutality still haunts the present. [S2E10] The Hour of Death