[1][2] Keo is a 2006 graduate of Archbishop Murphy High School in Everett, north of Seattle, where he played under head coach Terry Ennis.

As a senior in 2005, he played in the 2A state championship game at the Tacoma Dome; both teams entered undefeated, but top-ranked AMHS lost to Pullman by four points.

[3][4] Keo earned the starting job as a true freshman at the University of Idaho in 2006 under head coach Dennis Erickson, establishing himself as a leader in the secondary with 72 total tackles.

Injured early during the 2008 season, Keo redshirted and returned as a first team all-WAC conference safety as a junior in 2009, Idaho's first winning record since 1999, ending with a Humanitarian Bowl victory in Boise.

"[9] In the regular season's final game on January 3 against the San Diego Chargers, Keo intercepted a tipped ball off Philip Rivers which ultimately led to the game-winning touchdown drive.

[21] In Idaho on February 13, 2016, six days after the Super Bowl win, Keo was pulled over by the state police in Ada County for having a broken taillight.

Keo later pleaded guilty to misdemeanor DUI, had his driver's license suspended and was ordered to serve a year of probation and pay a $952.50 fine.