Richter is a character in Hotline Miami.
He first appears to the player in the latter half of Jacket's story line, standing next to the broken corpses of the nearly-identical shop and bar owners. Richter responds to Jacket's presence with disdain, generally urging the player to leave the establishment.
It is also hinted that Richter and Beard might be one and the same due to the fact that if one looks closely both have the same face/eye sprite model. Another theory that reinforces this is the fact that Richard, the Rooster mask character tells this to Jacket in one of his nightmares:
"Someone you know is not who you think they are."
Beard is being "replaced" by Richter in Jacket's nightmares as a result. This might have to do with the fact that he was hired by the Janitors to possibly debrief Jacket and eventually eliminate and anyone associated with him should he not survive his encounter with Biker. Or at least that's what we are lead to believe.
He is later found in Jacket's apartment, sitting on the couch, having just slain Hooker. After a brief conversation, Richter will shoot Jacket. Eventually this leads up to Chapter 12, Trauma, wherein Jacket finds himself in the hospital due to his injuries. After escaping, Jacket confronts Richter in a jail cell in the police station during Chapter 13, Assault. Richter reveals he does not himself understand the events at play and shooting Hooker was "nothing personal". The player can either shoot him, then strangle him to death or spare him.
During Richter's stay in Jacket's apartment he is wearing the Richter mask. This same mask can be found and picked up on the final floor of Chapter 13. If worn, the player starts the chapter with a silenced uzi, the same weapon Richter used to kill Hooker and to shoot Jacket in his nightmares.