A confidential internal memo obtained by The Associated Press says that the international aid group Doctors Without Borders found a pattern of abuse and sexual exploitation by some local and foreign staff working in Chad along the Sudanese border. The organization said it launched the monthslong investigation in response to AP reporting that women had accused staff of sexually exploiting them in displacement sites in Chad. Hundreds of thousands fled there from Sudan’s civil war. Doctors Without Borders is one of the largest employers and biggest aid organizations in eastern Chad's refugee camps. It says that the cases represent a breach of its values and that it has implemented new recruiting and complaint systems, though it recognizes much work remains.