The case came to the attention of prosecutors in December 2000, when social services alerted them to the possible sexual abuse committed by an unemployed couple against their own four children, AFP news agency reported.
The children, once they had been placed in foster care, told investigators they had been fondled, raped, coerced into performing sex acts and forced to watch pornographic films.
The children named other individuals involved, some of them neighbours.
Police seized sex toys and pornographic videos from the family apartment, where the illicit sex sessions allegedly took place.
In 2001, other members of the alleged ring, including a bailiff and his wife, a taxi driver and a priest, were placed under investigation.
Twenty people were initially arrested in connection with the alleged paedophile network.
One suspect committed suicide while in detention, while another was declared unfit for trial.
The trial is expected to last six weeks. |