Charles Manson smuggled a mobile phone into his high-security prison cell and used it to call contacts in at least four states and record messages that were later broadcast on US television.
The former cult leader convicted of inspiring followers to carry out a series of gruesome murders in the late 1960s, was caught with an LG phone under his mattress when officers searched his cell at Corcoran State Prison in California last April.
Days earlier, the TV show Inside Edition had broadcast several recordings purporting to be of the 76-year-old. One of them featured him singing, in a husky, high-pitched voice: "I've seen the world spinning on fire, I've danced and sang in the devil's choir."
A prison spokesman said: "It's troubling... since he's a person who got other people to murder on his behalf."