"I would like to thank the University of Iowa and football coaches for the opportunity," Derby said in a university release. "Unfortunately, I don't feel this is the best fit for me personally to reach my goals as a student-athlete.
"I especially wish my brother (Zach Derby) the best of luck in the coming year. I will miss all of my teammates, family and friends who have supported me here. Good luck to everybody. Once a hawk, always a hawk."
Zach Derby is a walk-on tight end. Their father, John, is a Hawkeye alum who played linebacker at the school.
"A.J. has asked for his release, which has been granted," Iowa Coach Kirk Ferentz in the school's press release. "We are sorry to see A.J. leave the program. He has been a positive member of our team and a pleasure to coach over the past two years. We wish him the best as he moves forward with his career."
Derby grew up in Iowa City and led Iowa City High to the 2009 Class 4A State Championship in football. Zach and A.J. started their high school careers at Iowa City West High and then transferred to City High.
A.J. Derby graduated early from City High and enrolled at Iowa in January of '10. He was brought in as a quarterback and moved up to No. 2 on the depth chart last fall.
Authorities arrested Derby in early October for fourth-degree criminal mischief and public intoxication at an Iowa City bar. He was suspended for two games.
Shortly after his return to the team, Ferentz announced that Derby would be switching from quarterback to linebacker. He embraced the move at the time.
"I'm not really looking in the past," he said on Oct. 22. "I'm looking forward. It was a hard decision, but I'm looking forward. I'm excited about this opportunity."
Derby played in nine games as a redshirt freshman in 2011, completing three of six passes for 30 yards and recording one solo tackle on special teams.
Derby was a highly-regarded recruit coming out of high school. He participated in the prestigious Army Bowl all-star game.