Cleotha Staples, one of the founding members of the renowned Chicago soul and gospel group the Staple Singers, died Thursday (Feb. 21) after a long bout with Alzheimer's disease. She was 78.

According to Chicago Tribune, the Mississippi native was suffering with the disease for 12 years and was under 24-hour medical care. Her longtime nurse was with her when she passed away at 11:11 a.m. CT in her condo on the south side, reported her sister, Mavis.

Cleotha, or "Cleedi" as she was affectionately called, was the oldest of the Staple Singers, which consists of her sister Mavis, her brother Pervis and leader Roebuck "Pops" Staples, who passed away in December 2000. Cleotha's sister, Yvonne replaced Pervis many years later.

The group rose to prominence in the late '60s and early '70s with a string of No. 1 R&B hits including 'I'll Take You There,' 'Respect Yourself' and 'If You're Ready (Come Go with Me)' on Stax Records.

"Her twang as a vocalist was unique," said producer Al Bell about Cleotha's vocal contributions to the group. "And it was the color, the spirit and the attitude of Cleotha, too, that made the group special. She was always complimenting, encouraging and pushing everyone else along."

In 1999, Cleotha was inducted into the Rock and Roll Hall of Fame as a member of the Staple Singers and received a lifetime achievement award from the Grammys in 2000.

Cleotha Staples leaves behind her sisters Mavis and Yvonne, and her brother, Pervis. Funeral services are pending.

Watch the Staple Singers' Perform 'If You're Ready' on 'Soul Train'

Watch the Staple Singers' Perform 'Respect Yourself' Live