Coach Gary Harrell’s Bison finished second in the Mid-Eastern Athletic Conference in 2012 with a 7-4 record. (Jonathan Newton/The Washington Post)

After leading the Howard University football team to its first winning season since 2004, Coach Gary Harrell has taken a voluntary leave of absence for the 2013 season with plans to return, the university announced Monday. Rayford Petty, the team’s defensive coordinator the past two seasons under Harrell, takes over as interim head coach, effective immediately.

In a statement, Harrell said he made the decision “with sadness” to deal with “personal and family issues” and that he hopes to return in 2014. A university spokeswoman declined to provide further details.

“In making this decision, I thought deeply about my extended family, my players and coaches,” Harrell said in the statement. “At this time, my personal and family issues make it impossible for me to give them 100 [percent] and anything less than that is unacceptable to me.”

An undersized wide receiver who helped the Bison win a Mid-Eastern Athletic Conference title in 1993, Harrell returned to his alma mater in 2011 and has posted a 12-10 record in two seasons. He took over a team that had won four games the previous three years, going 1-10 in 2010.

Howard halted a 28-game conference losing streak and earned five wins in Harrell’s debut season before improving to 7-4 in the fall. The Bison won six conference games to finish second in the Mid-Eastern Athletic Conference behind Bethune-Cookman, despite missing several key players early in the season to suspensions related to improper textbook benefits. Last week, Harrell was honored by the D.C. Touchdown Club as the local college coach of the year at its inaugural awards dinner.

Petty served as defensive coordinator at Howard during Harrell’s playing career and returned to lead the Bison to a 25-30 record in five seasons as head coach from 2002-06. He was among several assistants brought in by Harrell with connections to the Bison’s success in the mid-1990s.

Petty did not return phone calls seeking comment.