Empress Ma
Since 82 CE, Liu Qing, Zhang's son from his concubine Consort Song, had been the designated heir, secured by the favor of Empress Ma. However, Ma's death in 79 CE made Lady Dou the empress, and—aiming to develop her family's power—she adopted Prince Zhao with the intention of installing him as heir. As a result, when Song became ill in 82 and asked for herbs, Dou falsely accused her of planning to use the herbs for witchcraft against Zhang. Dou then ordered Cai to interrogate Consort Song and her sister, another imperial consort, to force a confession; they both killed themselves. Believing Dou's accusation, Zhang replaced Liu Qing with Prince Zhao as heir.