Trial Set for Brotherhood Officials in Deaths at Anti-Morsi Riots Manu Brabo/Associated Press Supporters of Mohamed Morsi in Giza, Egypt, on Sunday. The Muslim Brotherhood's power has dissipated in recent weeks. CAIRO - Three top officials of Egypt's Muslim Brotherhood will go on trial on Aug. 25, on charges of inciting members of their group to kill rioters in front of its headquarters during the upheaval that led to President Mohamed Morsi's ouster on July 3, a Cairo court ruled on Sunday. Although the authorities have detained dozens of Brotherhood members since Mr. Morsi's fall from power, the case against the group's spiritual leader, his deputy and another key figure is the first to be scheduled for trial. The pending prosecutions are a new blow to the Brotherhood, which emerged as the country's strongest political movement after the ouster of President Hosni Mubarak in 2011, but has seen all of its newfound power stripped away in a matter of weeks. The scheduling of the trial will most likely further complicate intensive political and diplomatic efforts to persuade Mr. Morsi's supporters to break up two large sit-ins in Cairo that they have committed to maintaining until he is restored to power. Egypt's new military-backed government has said it would not let the sit-ins continue indefinitely, but many fear that efforts to forcefully disperse the protesters would unleash new violence. Envoys from the European Union, Qatar, the United Arab Emirates and the United States have tried to help broker a solution. The prosecutions could be an effort to put more pressure on the group to strike a deal to end the current crisis, said Shadi Hamid of the Brookings Doha Center. The case concerns events during the final days of Mr. Morsi's tenure, when hundreds of rioters - equipped with stones, Molotov cocktails and firearms - attacked the Muslim Brotherhood's headquarters in Cairo and tried to burn those inside alive. Police officers in the area during the attack did not intervene, and a few men inside the darkened building fired guns from the windows. Health officials said eight people were killed outside the building, and a video posted online showed one badly beaten man being dragged from the building. Accused of incitement to murder in the case are the Brotherhood's supreme guide, Mohamed Badie; his deputy, Khairat el-Shater; and another official, Mohamed Bayoumi. Three other defendants in the case have been charged with murder and arms possession, and an additional 29 people have been accused of using force, terrifying residents and attacking a police officer, state news media reported. Mr. Hamid said the prosecution represented an escalation of the military's campaign against the Brotherhood. "It reflects a real desire on the part of some in the organization to use this opportunity to destroy the Brotherhood," he said. Even under Mr. Mubarak, whose security services routinely detained and tortured Brotherhood members and other Islamists, the supreme guide was mostly left alone. A serving supreme guide of the Brotherhood has not been arrested since 1981, before Mr. Mubarak came to power. In a separate case, the prosecutor general ordered the detention of Mr. Morsi's former chief of staff and his deputy for 15 days for investigation into charges that they incited the detention and torture of protesters by Brotherhood members in 2012. Mr. Morsi, who has been detained in an undisclosed location since his ouster, is also under investigation for purported collaboration with the Islamist militant group Hamas and his escape from prison during the uprising that led to Mr. Mubarak's ouster. Also Sunday, authorities at Cairo airport denied entry to Tawakkul Karman, the Yemeni activist and Nobel Peace Prize winner, who had flown to Egypt to join a pro-Morsi sit-in, state news media reported. They did not give a reason for refusing entry to Ms. Karman, a member of Yemen's largest Islamist party, who won the prize in 2011 for her role in the uprising that led to the fall of that country's president, Ali Abdullah Saleh, and who has recently spoken out against Mr. Morsi's removal from power.