Jeremy Bamber, who has served more than 40 years in prison for murdering five members of his family, has been banned from communicating with the media.

Bamber was convicted in 1986 by a 10-2 majority of shooting his adoptive mother and father, his sister and her six-year-old twins at the parents’ family farmhouse in Essex a year earlier. He has always protested his innocence.

The 65-year-old has long relied on telephone interviews and exchanges of letters with journalists as a way to draw attention to his case. But his campaign group has told the Guardian he is no longer allowed to send letters to journalists, nor receive them, nor is he allowed to talk to reporters by phone.…