Two charity workers have been stabbed to death by unidentified assailants in southwestern Bangladesh, officials said Saturday. Tapan Kumar Roy, 30, and Liplal Marandi, 35, were attacked early Friday as they slept in their rented home in a village in Faridpur district, 65 kilometers (40 miles) southwest of the capital, Dhaka, said the area's chief government administrator Nasiruddin Khan. Police are investigating and have detained a suspect for questioning, police official Abdur Rouf told The Associated Press by telephone. The motive for the killings was unclear.