Lewis Foster was a deputy to the Sheriff, like a son to him, after the murder of his sister Caroline (the murderer was apparently never caught). He helps the Sheriff capture Ackerman in the barn and then aids him in taking shots at Marcus Williams as the ex-officer tries to get away.
Foster goes into the school to rescue Maggie on orders from the Sheriff and never makes it out. He fights with Ackerman, who manages to stab him. Marcus later finds his body, chest bare and slit open down the middle.
Foster was a member of the Shepherd Organization, part of the Director's cell.