Nadia Savchenko, a pilot who served as an infantry volunteer fighting rebels, was making her closing statement.
She denies directing mortar fire at the Russian journalists in June 2014.
She says she has not had food and drink since Friday.
Speaking Ukrainian, she mocked the judges in the court in the south Russian town of Donetsk, saying they proved that Russians were "fascists".
A translator read out her formal, final statement in which she proclaimed her innocence and described her trial as a "farce".
The EU and US have both called for her immediate release.
A verdict in the case is due to be delivered on 21 and 22 March but her lawyers have said she will not survive that long unless she is force-fed.
If convicted, she could face 20 years in prison.
This was a brief hearing but a dramatic one.
Despite five days refusing food and water, by her own account, Nadia Savchenko walked into court herself and stood throughout - her cage surrounded by armed guards.
When she spoke, her voice was strong - and angry.
At one point she leaped on to the bench and showed the three judges her middle finger - a furious demonstration of what she thinks of Russian justice.
Her formal statement was read by a translator, in which she called President Vladimir Putin a "tyrant" and her trial a "farce" directed by the Kremlin.
Some supporters had brought yellow flowers, to match the Ukrainian flag, and as the judges left to consider their verdict over the next 12 days, Nadia Savchenko stood with her hand on her heart leading them and her relatives in a passionate verse of the Ukrainian national anthem.
She vowed to keep up her hunger strike until she is returned home.
But outside court, her lawyers warned that she would not live that long unless she was force-fed.
She was captured in the summer 2014 at the height of the fighting between Ukrainian troops and pro-Russian rebels.
A pioneering female combat pilot in the Ukrainian air force, where she held the rank of lieutenant, she had enlisted in a volunteer infantry unit, the Aidar Battalion, to fight in eastern Ukraine.
She is charged with acting as an artillery spotter and directing the bombardment of a rebel checkpoint, in which two Russian state TV journalists, Igor Kornelyuk and Anton Voloshin, were killed.
Denying the accusation, the 34-year-old insists the whole case against her is politically motivated, and she has become a symbol of Ukraine's resistance against Russia.
She says she was kidnapped by rebel fighters at least an hour before the attack in which the Russian journalists were killed, and later handed over to the Russian authorities.
Russian prosecutors say she secretly crossed into Russian territory herself.
Ukrainian diplomats in the Russian region of Rostov say judges in the case are refusing to issue any more permits to visit Ms Savchenko in prison.
Her relatives have also used up all their visiting permits, meaning a group of Ukrainian doctors en route from Kiev to visit her will also not be given access.
The EU has expressed concern about Ms Savchenko's wellbeing, and Nobel prize-winner Svitlana Aleksievich is among more than 4,300 signatories to an open letter urging European leaders to act to secure her freedom.
Relations between Russia and Ukraine - along with its Western allies - have deteriorated since the events of 2014 in Ukraine.
Moscow annexed the Crimean peninsula that March after an unrecognised referendum on self-determination, and is accused of covertly supporting the rebels in the bloody conflict which later divided eastern Ukraine.
Source: BBC News