But what's most striking in the trial that opened on Monday in the northern French town of Douai, is that not only his parents stand accused of his death, but two doctors - in other words those who should have been best positioned to protect him - are also facing prosecution.
Marc was found dead on January 25, 2006 at his mother's home.
An autopsy revealed that he had died of a cerebral haemorrhage caused by multiple punches in the face. But it also showed that he had fractured ribs, bruising to his back and other scars including cigarette burns covering the whole of his body that indicated previous beatings.
On trial are the boy's step father, David Da Costa, accused of murder by torturing and repeatedly beating the child, and his mother, Isabelle Gosselin, for complicity in a crime.
Alongside them in the dock are seven other people. They include Marc's grandparents, his aunt and uncle, a childminder who was the mother's best friend and two doctors, Christian Tirloy and Michel Vellemans. All stand accused of failing to assist a person in danger.
According to reports compiled by police after his death, Marc's life could have been saved several times in the weeks leading up to January 25.
But his mother always explained any evidence of bruising on his face to family and friends as being a result of the five-year-old's self-harming. Gosselin told them that her son hit his head against the wall and threw himself downstairs.
And that was a story she repeated to the two doctors, one of whom saw Marc at the end of December 2005 and the other in January, a week before his death.
Both doctors insist that their suspicions were never aroused and that they considered Gosselin to be a "good mother" and one beyond suspicion.
Alice Cohen Sabban, a lawyer for Vellemans, who examined Marc in January, told French television that the doctor had noticed several scratches, but had accepted Gosselin's explanation of how the boy had acquired them and recommended she take him for a psychiatric evaluation.
"He made a diagnosis based on what the mother told him and what he saw," she said.
"And he came to the conclusion that the boy wasn't being mistreated but that it was a behavioural problem - his behavior - that was the cause of his bruising and scratches."
For Alain Reisenthel, one of the prosecuting lawyers however, that explanation is unsatisfactory.
"If the doctor had seen the child and conducted a full examination, he would have stopped the mother from leaving the surgery and contacted the police," he said.
Furthermore Reisenthel believes that all of the seven people on trial for failing to assist a person in danger played a part in the death of the child.
"If just one of them had intervened, Marc would still be alive," he told journalists.
The trial is being seen as not just one about child abuse, but also about the apparent "indifference" of those who should have been in a position to prevent or stop it from happening.
It's set to run until November 7
|Enfance et partage - a French association to protect and defend children against abuse|