For the second time in less than two years, California prison officials caught Charles Manson, mastermind of one of the most notorious killing sprees in U.S. history, with a cellphone behind bars.

Guards at Corcoran State Prison found the phone on Jan. 6, according to prison spokeswoman Terry Thornton. Manson was charged with violating prison rules, but not with a crime, because there is no law in California that prohibits inmates from possessing phones. Thornton declined to provide any details about where Manson got the phone, or who he called, saying the case is still under investigation.

Manson called people in California, New Jersey and Florida with an LG flip phone found under his prison bunk in March 2009, Thornton said.

Thirty days were added to his sentence for the first offense, officials said. Manson is technically eligible for parole but will almost certainly die in prison for ordering the ritualistic murders of actress Sharon Tate and six others in 1969.