CHICAGO (AP) — In a family of vocalists, it was Cleotha Staples’ smooth and velvety voice that helped set apart the sound of the influential and best-selling gospel group The Staple Singers.

Staples, the eldest sister and member of the group her father Roebuck “Pops” Staples started in the 1940s, died Thursday at age 78. She was at her Chicago home and had been suffering from Alzheimer’s disease for the past decade, said family friend and music publicist Bill Carpenter.