Keo resigned with the Broncos on Tuesday, Mike Klis of 9News.com reports.
Keo rejoins the team just a few days after they parted ways. The safety was suspended for the first two weeks of the season but is now able to take the field again. He'll compete with rookies Justin Simmons and Will Parks for a backup safety position.
Braunecker worked out on the side of practice on Thursday as he recovers from an ankle injury, Brad Biggs of the Chicago Tribune reports.
Braunecker is an undrafted rookie who faces an uphill battle to make Chicago's roster, as he's buried on the depth chart. The sooner he can return to action the better, and it appears he's nearing a return now that he's been able to at least work out on the side. Rob Housler and Gannon Sinclair will likely continue to see extra reps as long as Braunecker is out.
Ferguson has been handed a four-game suspension for a violation of the NFL's policy on performance-enhancing substances, Jeff Dickerson of ESPN Chicago reports.
After notching three tackles in four games, Ferguson was placed on season-ending injured reserve in October due to a nagging knee injury. Thus, his ban won't kick in until he's healthy enough to take the field during the 2016 campaign.