Two police officers accused of using excessive force against a 28-year-old man who died in police custody in June made their first court appearance on Tuesday, in a case that human rights advocates say is a test of the government’s willingness to root out a culture of police abuse. During the hearing, lawyers for the family of the victim, Khaled Said, gave a judge a witness list, including people who they said saw the officers, Mahmoud Saleh, 33, and Awad Ismael Suleiman, 31, beat Mr. Said to death. Two autopsies conducted by the authorities concluded that Mr. Said had choked on a packet of marijuana. The two officers said nothing during the hearing, and the trial was adjourned until Sept. 25.