By the end of the 1960s, the trend of exploring psychedelia in music was largely in retreat. LSD was declared illegal in the US and UK in 1966. The linking of the murders of Sharon Tate and Leno and Rosemary LaBianca by The Manson Family to Beatles songs such as "Helter Skelter" contributed to an anti-hippie backlash. The Altamont Free Concert in California, headlined by The Rolling Stones and Jefferson Airplane on December 6, 1969, did not turn out to be a positive milestone in the psychedelic music scene, as was anticipated; instead, it became notorious for the fatal stabbing of a black teenager Meredith Hunter by Hells Angels security guards.