Robert Turbin has been suspended four games for using performance-enhancing drugs.

He will be eligible to return to the Indianapolis Colts on October 1, ahead of the team's Week 5 game at New England on Oct. 4.

"A urine sample I provided to the NFL has resulted in a positive test of a banned substance under league policy with regards to Performance Enhancing Substances. It absolutely kills me that I allowed this to happen," Turbin wrote on Twitter. "It has always been a priority in my life to display a high level of leadership both on and off the field. I strive to be a person that people can look up to and strive to exemplify the definition of hard work.

"Unfortunately, I have made a mistake. A mistake that will not only have personal consequences, but will affect the Colts organization, an organization that I am extremely appreciative to be a part of. For that, I am truly sorry."