
Basically the OP says that this guy is heavily involved in the story, because:
1) He appears in many, many places (ie: walking through a hallway after Faith's death, standing in line while you talk to Grendel, DRIVING THE TAXI SNOW WHITE IS IN BEFORE HER "DEATH")
2) His tie is patterned with a bunch of crooks (staffs that shepherds use)
3) Episodes 3, 4, and 5 are named "A
Crooked Mile," "In
Sheep's Clothing," and "
Cry Wolf"
Which means that this is The Boy Who Cried Wolf, and that his motivations would be aimed at Bigby, probably for revenge for him eating all his sheep, which he'd carry out by killing anyone that Bigby cares about.
Of course in the game's current state, that theory can get thrown out the window with Snow being alive and well (it wouldn't make sense for the killer to drive Snow somewhere, drop her off, then later on kill a troll glamoured as Snow roughly an hour or so later) and the fact that so far there have been no noticeable sightings of the guy in Episode 2.