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Singer and guitarist Ray Collins—who helped found the Mothers of Invention with Frank Zappa—died of a heart attack on Monday at the age of 76. Collins first met Zappa in 1961 and asked the guitarist to join his cover band The Soul Giants a few years later. Zappa eventually got the group playing their own original material before transforming the band into the Mothers of Invention. Collins sang lead on the group’s first album Freak Out! in 1966 and their second album Absolutely Free in 1967 before quitting the band. He then briefly reunited with the Mothers of Invention a year later on their 1968 doo-wop concept album Cruising with Ruben & The Jets. Collins reportedly spent the last years of his life working out of a van in Claremont, CA, while still receiving royalties for “Memories of El Monte,” a song he co-wrote with Zappa.