* Ousted leader charged with complicity in murder
* Prosecution says to draw on fact-finding committee report
* Case points to challenge facing Egypt transitional justice
* Next hearing set for June 8 (Adds hearing adjourned, prosecution to offer new evidence)
By Alexander Dziadosz and Yasmine Saleh
CAIRO, May 11 (Reuters) - Former Egyptian president Hosni Mubarak was back in court on Saturday for a retrial on charges of complicity in the murder of protesters, reopening a case that has shown the difficulty of transitional justice in post-revolutionary Egypt.
Mubarak and his former interior minister, Habib el-Adli, were convicted and sentenced to life in prison last June for failing to stop the killing during the 2011 uprising that swept him from power. But a court ordered a retrial in January after accepting appeals from both the prosecution and the defence.
Each cited different shortcomings with a trial that was criticised for the weak evidence offered by the prosecution.
After a three-hour session broadcast live on state television, during which the charges were read and the prosecution made a statement, the proceedings were adjourned. The next hearing was set for June 8.
The prosecution promised to offer new evidence including some taken from the report of a fact-finding committee set up by President Mohamed Mursi in 2012.
The findings were not made public as promised by Mursi, but leaks published by Britain's Guardian newspaper last month alleged the military was involved in torture, killings and forced disappearances during the uprising, which it denied.
Mubarak, 85, sat upright on a hospital gurney as he was wheeled into a cage where defendants appear. As he entered, some in the courtroom chanted: "The people want the butcher executed."
Wearing aviator sunglasses, he raised his arm to confirm his presence as Judge Ahmed al-Rasheedy read a list of the accused and said, "Present." He waved his arm in denial when asked by the judge to respond to the charges.
His two sons, Alaa and Gamal, stood alongside him dressed in white prison uniforms. They face charges of corruption.
The retrial at a police academy on the outskirts of Cairo had been due to begin last month but was delayed when the previous judge recused himself.
Mubarak is being held at Torah Prison on the outskirts of the capital. He remains in jail despite release orders because he faces charges in a separate corruption case.
Mubarak, Adli and four of his former top aides are accused of involvement in the killing of more than 800 protesters who died in the 18-day uprising. Two other Interior Ministry officials face lesser charges.
PROTEST OUTSIDE THE COURT
Mubarak's imprisonment last June was a historic moment - he was the first ruler toppled by the Arab Spring revolts to stand trial in person. But the case exposed the difficulties of attaining justice when the judiciary and security forces are still largely controlled by figures appointed during his era.
Adli's four aides were exonerated due to the weakness of the evidence, and the judge convicted Mubarak and Adli on the grounds of their failure to stop the killing, rather than actually ordering it.
The prosecution had complained that the Interior Ministry had failed to cooperate in providing evidence.
Outside the court, a small group of protesters gathered under a baking sun held aloft banners demanding justice.
"Your mother misses you, Ahmed," read one banner, referring to a demonstrator killed in 2011. A rival group of a dozen Mubarak loyalists held aloft pictures of the former president dressed in military uniform and business suits.
Many Egyptians have been frustrated by the failure of courts to bring officials to account for the violence during the uprising and for what they see as decades of corruption and police abuses preceding it.
On Wednesday, a court refused the appeal of a verdict that exonerated two dozen defendants over an incident during the revolt in which men on camels and horses attacked protesters in Cairo's Tahrir Square. (Additional reporting by Yasmine Saleh; Writing by Tom Perry; Editing by Mark Heinrich and Sonya Hepinstall)