Seated on a woven mat in a refugee camp in eastern Chad, Dr. Sondra Crosby of the Boston Medical Center listened with mounting distress as the women of Darfur came forward, one by one over 12 days, to tell her their stories of rape, beatings, hunger, and humiliation.

Their suffering had begun in the ravaged villages of their native Darfur in western Sudan after war broke out in 2003, but it didn't stop when they fled across the border into what they hoped would be the safety of refugee camps in eastern Chad. It goes on still, leaving thousands of women facing the specter of sexual assault each time they leave camp to collect firewood or visit the local market.

It is an endlessly unfolding tragedy the world hasn't summoned the will to do much about. Crosby and her colleagues suspected that six years into the conflict, no one had yet fully grasped the extent of the crisis of sexual crimes, and the relentless toll it is inflicting on its victims.

And so she and three other Boston-area medical specialists interviewed 88 women in November in eastern Chad. This morning they released the results in a report that offers unprecedented and disturbing details on the long-term effects of the assaults - as well as fresh evidence of the continuing violence against the women of Darfur, years after they fled the battlefield.

The study was issued by the Cambridge-based Physicians for Human Rights, partnering with the Harvard Humanitarian Initiative, two organizations with long track records in investigating rights abuses in conflict areas. While the use of rape as a weapon of war in Darfur has been noted throughout the conflict, the new report provides comprehensive evidence from detailed, structured interviews as well as physical examinations of the victims.

The 88 women interviewed reported suffering 32 rapes. Of those, 17 occurred in Darfur and 15 in Chad. Seven women reported being the victim of gang rape in Darfur, and three women reported being raped more than once. For two of them, rape in Darfur was followed by rape in Chad.

"What is striking is the extent of rape and fear of rape in Chad itself," said Susannah Sirkin, deputy director of Physicians for Human Rights. "So it's a two-fold revelation of real horror and shame and sorrow, and really of failure."

The story of one woman, in particular, transfixed Crosby, who lives in Dedham with her five adopted children and has made it her calling to investigate cases of torture and abuse.