Then 'stoned and suffocated little boy, before stabbing him in the back'

They allegedly tied up his hands and feet and beat him with thorny stick

But youngsters later announced they were going to play a 'kidnap game'

Christopher Raymundo Marquez, 6, invited to play by five other children

A six-year-old boy has been brutally murdered by five other children during a macabre 'game of kidnap', Mexican authorities have revealed.

Christopher Raymundo Marquez was allegedly invited to play and collect firewood from a waste ground near his home in Chihuahua by the youngsters, aged 12 to 15.

But as they reached a stream, the children told him they were going to feign a kidnap. They tied Christopher's hands and feet together, before beating him with a thorn-covered stick, it is said.

They then reportedly stoned the youngster and suffocated him with the stick pressed against his neck, killing him. After he had died, one of the children even stabbed him in the back, it is alleged.

Killed: Christopher Raymundo Marquez , six, was tied up, choked, stoned and stabbed in the back. Five children aged 12 to 15 years old have apparently admitted to his brutal murder in Chihuahua, Mexico

Christopher's body was found buried face-down in a shallow grave in the northern Mexican city of Chihuahua early Saturday afternoon - two days after he went missing from his nearby home.

The alleged killers, a boy aged 12, two girls aged 13 and two other boys aged 15, had covered the hand-dug hole he had been dumped in with weeds and a dead animal, authorities said.

Police detailed the horrific circumstances surrounding Christopher's killing on Saturday night as they revealed that three of the child suspects are too young to be charged and tried under local law.

State prosecutor Sergio Almaraz said the youngster had been killed during a 'game of kidnap'. He added that the minors had admitted Thursday's killing in a poor neighborhood of the state capital.

The children, neighbors and friends of Christopher, had invited the boy to play and collect firewood - but had turned on him after telling him they were going to feign a kidnap beside the stream.

Mr Almaraz said: 'While they were playing, one of the 15-year-olds suggested to the others that they should kill Christopher. It wasn't planned. It was a condition of the game they played.'

Crime scene: According to authorities the children buried the six-year-old in a shallow grave after the torture

Authorities discovered Christopher's body after the mother of one of the 15-year-old boys phoned police to tell them she had discovered her son had participated in the murder.

He and the other teenage boy face criminal charges but the three younger children, who are under the age of criminal responsibility in Mexico (which is set at 14), cannot be tried.

A spokesman for the local prosecution service said: 'Because they're minors and very young they have very specific rights which are stipulated by law.

'All five children will undergo psychological and sociological studies to determine their family environments.'

Mexican Jail: Prosecutors have expressed concern over a killing that showed 'social decomposition' and an 'absence of values'. Three of the child suspects are too young to be charged. Above, Chihuahua prison

Christopher's mother, Tania, who reported him missing on Thursday night, said on Sunday her son's alleged killers had taken part in the search for him with their families before his body was found.

She said: 'What I want is justice. If justice isn't done, we'll make sure it's done with our own hands. I, as a mom, demand justice. How are they going to set these children free?

'They haven't done these horrible things to a dog, they've done them to a child.'

Christopher's death 'at the hands of five other children' has stunned Mexico. Prosecutors have expressed concern over a killing that showed 'social decomposition' and an 'absence of values.'