late in 88, however, a crime that dou xian committed threatened to cause even empress dowager dou to want him executed. liu chang (劉暢), the marquess of duxiang, was favored by empress dowager dou for his intelligence, and dou xian became fearful that liu will divide his power. he therefore had liu assassinated and blamed liu's brother liu gang (劉剛), the marquess of li. several judges who were unafraid of dou xian, however, carried out a thorough investigation, and dou xian's involvement was discovered. empress dowager dou was enraged, and she put dou xian under arrest, and dou xian offered to lead an army against the north xiongnu (xiongnu having been divided into two since the times of emperor guangwu, with south xiongnu being a loyal vassal and north xiongnu being a constant nuisance, at most) to atone for his crimes.