The trial of Kyrgyzstan's former president has opened amid chaotic scenes in the capital, Bishkek.
There were clashes between police and the relatives of some of the 85 people killed in April, when Kurmanbek Bakiyev was ousted in a mass uprising.
It is alleged Mr Bakiyev ordered troops to open fire on protesters.
Mr Bakiyev has since fled into exile and is being tried in his absence. Twenty-seven ex-officials are also on trial in a huge concert hall.
The trial is the biggest in the ex-Soviet state's history, with some 130 witnesses expected to be called to give evidence.
Mr Bakiyev, who fled to Belarus, and five of the accused, are being tried in absentia.
The most prominent of the 22 defendants in court were former defence minister Bakytbek Kaliyev and the deputy head of the state bodyguard service Nurlan Temirbayev.
Relatives of some of the victims held angry demonstrations near the improvised courtroom in the vast Palace of Sports, vowing revenge.
Inside the courtroom there were reports of relatives hurling abuse at the accused.
Rights activists are concerned the hearing may amount to a show trial.
"You could not possibly call this an unbiased court which is going to give an objective estimate of what happened on 7 April," the head of Citizens Against Corruption, Tolekan Ismailova, was quoted by AFP as saying.
The trial comes after months of political turmoil following the ousting of Mr Bakiyev.
In June the south of the country - the ex-president's stronghold - saw bloody clashes between the Kyrgyz majority and ethnic Uzbeks in which at least 400 died.
The new authorities, led by President Roza Otunbayeva, have since created the first parliamentary democracy in Central Asia after elections in October.
However the country remains divided. In what was largely seen as a shock result, the opposition hardline nationalist party Ata Zhurt - whose leader was a minister under the former president - narrowly won.
The party has strong backing in the south among ethnic Kyrgyz and wants to go back to a presidential form of government.
However it did not win an overall majority and must now form a coalition with one of the four other parties.