It was the scene of such gruesome violence it would haunt the police who were first on the scene forever.
In the early hours of August 7, 1985, officers arrived at White House Farm in rural Essex after they had received a frantic call about a possible domestic incident.
The man who had made the call - Jeremy Bamber - was waiting for them outside.
He claimed he had received a chilling phone call from his father, Nevill, telling him his younger sister, Sheila, was "going beserk" with a gun.
Former model Sheila, known as Bambi, had suffered from mental health problems and Bamber hinted she could be suffering from a relapse.
The scene that greeted police that night was one of brutal destruction and a family home covered in blood and dead bodies.
Nevill and his wife, June, had both been slaughtered along with Sheila's young twin sons, Nicholas and Daniel.
Sheila herself was also dead next to a shot gun with a gunshot wound to her head.
At first police believed that Sheila had committed the murders before turning the gun on herself but the truth was much more sinister.
Revelling in the subsequent media frenzy that surrounded the murders, Jeremy Bamber played the role of the grieving son but in reality, the24-year-old was the one who had slaughtered his family in a vicious execution-style killing spree.
Now, in the brand new series of Faking It: Tears of a Crime, a panel of British experts in psychology, body language and speech analyse video footage of Bamber attending his stepparent’s funeral frame-by-frame.
They reveal the moment he gave away the truth by pouting like a ‘sulking child’ and faking sadness, fully in the knowledge that he had been the one who gunned down his family in cold blood.
Shown on camera by his adopted parents' coffins, Bamber seems to be visibly devastated.
Walking solemnly behind the coffin bearers with his hand on his face, Bamber’s "deep grief is obvious", as noted by the televised news report.
But as body language expert Cliff Lansley reveals, there are several tell-tale signs in Bamber’s facial expressions that strongly indicate that he was feigning sadness all along.
He explains: "Genuine sadness has to be accompanied with a dropping of the lip corners with two muscles here which pull the lip corners downwards.
"When you have sadness that’s intent enough to raise the brows that high, we always see engagement of the mouth muscles drawn down, and that isn’t present here.
“All we see on the lower half of the face is the slight jaw drop with the mouth open. But there is no indication of the muscle movement that we’d need to see to judge this as reliable sadness.”
Analysing another angle of Bamber at the funeral, Cliff identifies the moment Bamber gives away his guilt by pouting like a ‘sulking child’ for the cameras, rather than displaying genuine remorse.
He said: “He’s created a horseshoe but he’s using the wrong muscles. And how do we know that? It’s because we can see the dimpling as we move in, we can see the crease on the chin boss and we can see the pout on his bottom lip.
“Some people call that a pout, and we see it with sulking children who are faking sadness. And from this, as far as sadness is concerned, we can be sure that he’s faking it. I’m very confident that he’s not sad, this is a fake pose.”
Off camera, Bamber continued to behave strangely.
As forensic psychologist Kerry Daynes highlights, Bamber’s behaviour at the funeral was not what you would expect of someone who had just lost his entire family.
She explains: “He certainly put on a good show for photographers, but what TV viewers didn’t know was just a few minutes later Bamber seems to have made a very speedy recovery, because he’s on his way to the crematorium and he’s apparently larking about and making smutty jokes.
“So how was he able to do that after being in such a state of devastation just a few minutes beforehand?”
Following the funeral, Bamber’s attitude towards the death of his family soon turned from flippant to callous.
Kerry says: “Bamber set about trying to sell anything that was of any value in the farmhouse, and he even had his mum’s beloved dog put to sleep.
"He also tried to sell pictures of Sheila topless to a tabloid newspaper for £20,000.”
Eventually, Bamber’s lies caught up with him, and following new evidence coming to light and a lengthy trial, he was convicted of the murders and jailed in 1986.
But to this day Bamber continues to campaign for early release and to clear his name.
Speaking on audio tape in 2011, Bamber describes the last phone call he says he received from his father, who had apparently explained how his sister had gone "crazy with the gun".
As Professor of Linguistics Dawn Archer argues, Bamber’s reaction to this phone call was "too matter of fact" and lacked the appropriate emotion expected of someone who has been told their family’s lives are in danger.
She said: “It sounds an odd reaction to be so matter of fact without also telling us that it was an emotional upheaval.
“This is someone who is articulate, who is good with words, he can be convincing, and he can sound very credible. One of the things we need to be careful about is that truth and credibility are not the same thing.”
The White House Farm murders is one of the most tragic and controversial crimes in British criminal history.
Even now, 35 years on, the story has inspired TV documentaries, drama series and several books.
For the murders of his parents, his sister and his two nephews, Jeremy Bamber was sentenced to five life terms, and ordered to serve a minimum of 25 years.
Kerry Daynes claimed, Bamber’s feigned grief and lies were all part of his plan to get away with murder.
She said: “I think this is testimony to how intelligent he is and what a great illusionist he is, because he’s managed to create all of this white noise around this case when the truth is really simple: he did it.”
For Sergeant Chris Bews, who was first on the scene at White House Farm leading the three-man response team, there has never been any doubt in his mind that Bamber is guilty.
He said: “My two colleagues and I basically left the scene and we’d not gone 50 yards down the road when both my colleagues said ‘he’s done it, hasn’t he? He’s done it'
“They had gotten the same impression as well, that he was putting on a big act.”