Valentine made the announcement on Twitter on Monday. He thanked his family, friends and teammates for their support and the fans for ''all the love and unwavering encouragement.''
Valentine graduated in December with a journalism degree. He was limited to 10 games because of injuries this season. The native of Edwardsville, Illinois, made 10 tackles, including three sacks. He started 24 of his 36 games at Nebraska, making 76 tackles with seven sacks.