A mother in France allegedly helped her boyfriend rape her four-year-old son in prison. Sabrina Bonner, 25, and the boy's stepfather, Lionel Barthelemy, 31, are charged with multiple sexual assaults on the now eight-year-old child, who is currently in the care of social services.

Barthelemy was serving a three-year sentence for domestic violence of a previous girlfriend when Bonner visited him at the Toul detention centre in eastern France in February 2010. She brought her son with her, and apparently helped Berthelemy rape her own son.

According to prosecutors, the two adults covered the glass windows of a visiting room with black bin liners to hide the deed. Bonner blindfolded the boy and had him kneel on a chair and held him by the arms as Barthelemy raped him.

She is also accused of sexually assaulting her son at separate incidents from 2009 to 2010, recording those attacks with her mobile phone, and giving the phone's memory card to Barthelemy. She had surrendered to the police in May 2011, shortly before her imprisoned partner was due to be released.

Barthelemy has admitted raping his stepson, but said that the crime was an isolated incident that Bonner herself initiated.

Bonner, on the other hand, alleged that the prison rape and other incidents in which she filmed herself sexually assaulting her son were carried out under the threat of violence from Barthelemy.

The trial, held in Strasbourg, is due to run for three days, and is expected to tackle how prison staff failed to notice and prevent the act.

Although inmates are often given privacy when their partners visit them, Barthelemy wasn't supposed to get the same privilege because he was diagnosed with schizophrenia and was in jail for domestic violence.

The boy's solicitor, Yannick Pheulpin, will be initiating legal proceedings against the prison after the trial against Bonner and Barthelemy.

"Mrs Bonner made herself an accomplice to the crime by bringing her son to the visiting room twice on the same day: once in the morning when a first rape took place and a second time in the afternoon, knowing perfectly well that it was going to happen again," Mr Pheulpin was quoted by the AFP as saying.

Bonner and Barthelemy both face a maximum term of 20 years in prison if they are convicted.

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