Here is a link to an article about the new Channel 4 documentary. This will contain some new material.
https://www.maldonandburnhamstandard.co.uk/news/25392362.channel-4-jeremy-bamber-murders-documentary-air
The synopsis by the programme makers doesn't sound promising and nor do their previous "offerings" for anyone expecting a balanced investigative type documentary. I hope to be wrong but am expecting the usual, inexplicably popular, true crime/murder porn type offering. From the synopsis of the makers linked earlier by Curiosity,
"We are delighted to be continuing our successful production partnership with Channel 4
on another compelling piece of true crime television. We focused on speaking with
those who witnessed these crimes unfold first-hand, from investigators to journalists. This is a deep retrospective on a dark chapter in Essex history.”
The makers call it "true crime television" rather than a documentary or an investigation. The previous output of "Peninsula Television" doesn't fill me with confidence that this will be a serious documentary.
https://peninsulatelevision.com/true-crime/ Britain's Countryside Killers, Britain's Hotel Murders, Butchers of LA, A Perfect Scam, The Murderous Scissor Sisters, Murder at the Motel, Murdered (The Baby on the Beach), Confessions of a Crime Boss.
That is the first eight in their previous output of "true crime" television. It gets no better. I don't expect a serious offering from them but hope, probably against all reason, to be wrong.