Country music icon Glen Campbell, the Rhinestone Cowboy star who sold more than 45 million records, has died at the age of 81. One of the biggest stars of the late 1960s and 1970s, Campbell had 12 gold albums and 75 chart hits, including Wichita Lineman and By the Time I Get to Phoenix. His publicist Sandy Brokaw said the singer died on Tuesday morning at an Alzheimer's facility in Nashville. No cause was immediately given. One of Campbell's daughters, Ashley, said she was said she was "heartbroken". "I owe him everything I am, and everything I ever will be," she tweeted. Campbell announced in June 2011 he had been diagnosed with Alzheimer's disease and that it was in its early stages at that time. "I still love making music and I still love performing for my fans," he said at the time. "I'd like to thank them for sticking with me through thick and thin." Campbell started out as a session guitarist for the Beach Boys and producer Phil Spector. "I'm very broken up to hear about my friend Glen Campbell," Beach Boys co-founder Brian Wilson said. "An incredible musician and an even better person. I'm at a loss. Love and mercy." Jimmy Webb, who wrote Wichita Lineman, said on Twitter he was, "so very sad about the passing of [his] dear friend". Another country music legend, Dolly Parton, said she would always love him. "Glen is one of the greatest voices that ever was in the business," she said. "And he was one of the greatest musicians … he could play anything and he could play it really well." Lenny Kravitz echoed her sentiment, saying he was not just "an amazing solo artist", but "a genius studio musician".