PHOENIX – A half sister of Cindy McCain, wife of Republican presidential candidate John McCain, has died of Alzheimer's disease, the family announced.

Dixie Lea Burd, 74, died Tuesday in Phoenix. She had been in a nursing home for the past two years, her son Bob Burd said.

Cindy McCain and Dixie Burd had the same mother. Marguerite “Smitty” Johnson married Cindy McCain's father, the late James Hensley, in 1945.

“My family is deeply saddened by the death of my half sister, Dixie Burd. She had been very ill for quite some time, and it was difficult for loved ones to see her suffer,” Cindy McCain said in a statement released by the McCain campaign. “I am hopeful that my family's privacy will be respected at this time.”

Burd was a homemaker who later helped her family run six Hallmark stores in metropolitan Phoenix. Her son said Cindy McCain was protective of her and that they were close.

Another half sister, Kathleen Hensley Portalski, complained earlier this year that Cindy McCain wasn't treating her like family and announced that she was supporting McCain's rival, Democratic candidate Barack Obama.

Cindy McCain and Portalski have the same father. James Hensley founded Hensley & Co., the Phoenix-area Anheuser-Busch distributor, and Cindy McCain inherited her father's stake in the company.

A memorial service for Burd is set for Saturday in Mesa.