WASHINGTON, D.C.: The widow of late Islamic State group financial leader Abu Sayyaf was charged Monday for her alleged role in the death of US aid worker Kayla Mueller last year. Nisreen Assad Ibrahim Bahar, a 25-year-old known as Umm Sayyaf, was accused of conspiring to provide support to the violent extremists, forcibly detaining Mueller and other captives in the couple’s homes, where she was sexually assaulted by IS chief Abu Bakr al-Baghdadi. IS fighters claimed that Mueller, who was kidnapped in the Syrian city of Aleppo in August 2013, was killed in a February 2015 coalition air strike that buried her in rubble. US officials say the circumstances of her death remain unclear. She was 26. Abu Sayyaf was killed in May 2015 in a rare US commando raid inside war-torn Syria. Bahar was captured during the operation, and US forces also rescued a young woman from the Yazidi minority and seized a stash of firearms, the complaint recalled.