Apparently Jason West–co-creator of Call of Duty and co-founder of Respawn Entertainment–has left his Respawn team back in May. It has been stated that his reason for leaving Respawn Entertainment is to deal with family issues. Jason also left right after his lawsuit with Activision and EA was settled.
Jason West, along with Vince Zampella (co-founder of Respawn Entertainment), founded Infinity Ward back in 2002. The company then created the mega-hit we know and love today: Call of Duty. Both Jason and Vince were fired, however, from Infinity Ward back in 2010.