Iraqi prosecutors have asked for death sentences against five defendants in the so-called Anfal trial for the 1980s crackdown on Iraq's Kurdish population.
"Chemical Ali" is the cousin of late Iraqi leader Saddam Hussein
They include the alleged mastermind of the campaign - Saddam Hussein's cousin Ali Hassan al-Majid, known as "Chemical Ali" for his use of poison gas attacks.
Mr Majid has acknowledged ordering scores of villages destroyed, saying they were "full of Iranian agents".
The trial was adjourned until 16 April when the defence will sum up its case.
Saddam Hussein was a co-defendant in the case but charges against him were dropped after his execution in December 2006 over the killing of 148 Shia Muslims in the town of Dujail.
Four of the defendants are charged with war crimes and crimes against humanity but Mr Majid faces additional charges of genocide.
In his closing remarks, chief prosecutor Munqith al-Faroon asked the court to convict the five and give them the harshest penalty because they "did not have mercy on elderly people or women or children - not even animals or plants or the environment".
A sixth defendant - former Mosul governor Taher Tawfiq al-Ani - should be released however, the prosecutor said, because there was insufficient evidence against him.
During the 1987-1988 campaign, Iraqi Kurds were killed or displaced as a result of decrees and military operations forcing them out of "prohibited areas" of northern Iraq.
The government said it was carrying out counter-insurgency operations against Kurdish guerrilla fighters. Human Rights Watch estimates that at least 100,000 Kurds, mainly civilians, died in the operation.