Kieran Williams, 18, was last seen on April 18 last year, when he visited his mother's home in Sunderland and he was never heard from again.

Newcastle Crown Court heard six weeks later he was found buried, with multiple stab wounds, in a grave which had been concealed with sticks, leaves and litter.

Ben Cook, 19, of Fordfield Road, and Louis Hackett, 20, of Fordenbridge Square, both Sunderland, deny Kieran's murder and are being tried by a jury.

Forensic archaeologist and anthropologist Dr Julie Roberts examined the grave and was at the site when Kieran's body was found inside it.

Jurors were shown pictures of the "clandestine" burial plot, which was in an area surrounded by trees on open wasteland.

Dr Roberts told jurors when she first arrived at the site she saw an area of disturbance in the ground and added: "It was a rectangular shaped, a large, rectangular area that had been disturbed, with earth over the top, a large clump of soil and also twigs and branches situated on top of that, some of which looked a little bit out of place."

The doctor said she noticed "cuts" in the soil, where someone had dug into it and the area had the appearance of a "possible grave", which measured 2.5m by 1.7m.

Dr Roberts said on the late afternoon of June 2, after layers of soil had been removed, some dark blue fabric and then human remains were discovered in the grave, which was 75cm deep.

She added that a lot of research had been done into clandestine graves and told the court: "The average depth in the UK is around 40cm, which is usually the point at which it is possible just to cover the body.

"This grave was quite a good deal deeper than that."

Dr Roberts said a second, more shallow hole was found nearby, which could have been an initial attempt at digging the grave but was halted by the presence of a large tree root.

The doctor said Kieran was found fully clothed in the main grave and there was signs of burning to his anorak, trousers and sock.

She told jurors the state of the body indicated it had been in the grave for some time and added: "It was a well constructed, deep and well considered grave."

Dr Roberts said Hackett's fingerprints were found in the grave.

Forensic scientist Iain Peck told jurors in his opinion Kieran's body was burned when he was in the grave, where he lay on his left side.

Mr Peck told the court there was burning across the clothing and body of Kieran, mostly on the right side.

He told jurors: "With the superficial nature of the burning and the widespread nature of the burning across the body it indicated, in my view, a volatile, ignitable liquid had been poured and then ignited over the body."

Jurors have heard suffered "at least 20" stab wounds to his chest, torso, neck and had injuries to his hands, arms, legs and feet, which may have been fromtrying to protect himself.

The trial continues.

KIERAN WILLIAMS MURDER TRIAL: Teen's killers buried him in 'well constructed, deep and well considered grave', jury hears