Irrational have stayed pretty quiet on the Bioshock Infinite front this year, refusing to showcase the game at any of the summer expos, and there have been a list of studio departures over the past few months - a list that now includes two more members of the senior development staff.
Superannuation noted that Don Norbury and Clint Bundrick - reportedly the AI and combat lead designers on Bioshock Infinite - have now both left Irrational Games, abandoning the studio to take up new positions within Microsoft.
Hopefully this is simply a result of the game nearing completion rather than any last minute worries. There's a new trailer coming later this week, and the release date for the promising FPS is still pencilled in as February 26th, 2013.
You can find last year's Bioshock Infinite preview here.