The Cardinals placed Butler on the reserve/retired list Tuesday, Field Yates of ESPN reports.
A report from Mike Garafolo of NFL Network emerged Monday that Butler was mulling retirement as he tends to a personal matter. Indeed, Butler has opted for that route, thus saving the Cardinals a spot on the 53-man roster. In his stead, it appears the team plans to roll with Byron Murphy and Robert Alford (undisclosed) as its top two cornerbacks.