Reports within the last month, including from Sooners Illustrated, have suggested this possibility, but now it's 100 percent certain that the two will forgo their senior seasons and leave running back Brennan Clay behind as the only one of the three So Cal kids out of the 2010 class still at OU.
"We appreciate the contributions that Tony and Kenny have made during their time at Oklahoma," Stoops said. "We wish them both the best as they pursue their opportunities in the NFL."
Jefferson, a Second-Team All-American, led the Sooners with 119 tackles, including 3.5 for loss, and amassed 258 tackles throughout his three-year career.
He also tallied a pair of interceptions in 2012.
Stills, the lone returning receiver from OU's 2011 team, finished with team highs of 82 catches for 959 yards and 12 touchdowns.
The 6-foot-1, 190-pounder from Encinitas, Calif., racked up 204 receptions for nearly 2,600 yards in his career.
Both are projected in the third round or later, but they'll work out from this point on to improve that status.