He left the studio due to family issues.
The news fell today. Bonnie Ross, the iconic boss of 343 Industries, is leaving the studio and the Halo franchise, also being one of the founders of the study after the departure of Bungie. It seems, the departure is due to health problems in his family.
With a professional career that would be the envy of Ross, he will leave the gaming world after 25 years at Microsoft, where he helped develop games from legendary brands such as Halo, Gears of War, Jade Empire, Alan Wake, or the Primer of Mass Effect. We wish him the best for the future.