North Carolina running back Ryan Houston, the team's leading rusher last season, was reinstated Thursday as the Tar Heels took another step closer to completing the individual cases remaining in the ongoing academic- and agent-related NCAA investigations of the football program.

Thirteen players were suspended or held out of the season-opener against Louisiana State, and a 14th player was added to the list last Saturday. Five players remain in limbo as the investigation enters its third month.

Houston, who sat out the first five games, is the fourth player to be cleared to return. UNC did not specify why Houston missed the first five games.

Houston, a senior running back from Charlotte, led UNC with 713 rushing yards and nine touchdowns in 2009. He did not participate in spring practice in order to concentrate on academics.

Running back Shaun Draughn (held out of one game), safety Da'Norris Searcy (held out of three games) and safety Deunta Williams (suspended four games for preferential treatment) have already returned to UNC's lineup. Cornerback Kendric Burney, who was suspended six games by the NCAA for receiving improper agent-related benefits, is set to return on Oct. 23 for UNC's game against Miami.

Monday, the NCAA ruled defensive end Robert Quinn and receiver Greg Little "permanently ineligible" for accepting improper agent-related benefits and violating the NCAA's ethical conduct rules. UNC dismissed defensive tackle Marvin Austin for the same reasons on Monday.

Last Saturday, UNC ruled backup safety Jonathan Smith out for the season, without specifying a reason.

On the same day, the school withheld fullback Devon Ramsay for an unspecified reason. Ramsay played in the first four games before being sidelined by UNC.

In addition to Ramsay, the other players still awaiting their fate are defensive end Michael McAdoo, cornerback Charles Brown, defensive end Linwan Euwell and safety Brian Gupton.

McAdoo and Brown were listed on the preseason depth chart as starters, and Ramsay started two of the first four games. Euwell and Gupton are reserves on the defense.

jp.giglio@newsobserver.com or 919-829-8938