A 91-year-old retired Guatemalan general went on trial Friday for genocide in the second such case linked to the massacre of Indigenous people during the country's 1960-1996 civil war.

Benedicto Lucas Garcia is accused of involvement in the killing of more than 1,200 Ixil Maya people between 1978 and 1982, when his brother was president.

He is charged with genocide, crimes against humanity and forced disappearance, which carry a possible sentence of more than 100 years in prison.

Lucas Garcia followed the start of the trial by video link from a military hospital where he is serving a 58-year prison sentence for forced disappearance, rape and torture.

"I'm already desperate," the defendant, sitting in a chair in his hospital room, told the court's three judges.

He gave some personal information but did not make any further statements on the advice of his lawyer.

More than 80 expert reports will be presented and about 30 survivors will testify in the trial, lawyer Nery Rodenas, of the Human Rights Office of the Archbishopric of Guatemala, told AFP.

"We hope that the court considers that this is sufficient evidence to issue a conviction," said Rodenas, whose group supports survivors and relatives, none of whom attended the hearing.

"We pursue knowledge of the truth and access to justice that can lead to forgiveness and reconciliation between victims and perpetrators," Rodenas added.

On Friday, an expert witness presented reports of the exhumations of dozens of bodies with bullet holes and burns from mass graves.

Lucas Garcia served as armed forces chief during the 1978-1982 presidency of his brother Fernando Romeo Lucas Garcia, who died in 2006 aged 81.

He is accused of planning and executing dozens of massacres in villages in the western region of Quiche.

At an earlier hearing, Lucas Garcia, a father of seven, described himself as a "national hero."

The Ixil Maya population was accused by the military of serving as a support base for leftist guerrillas.

Around 1,300 Indigenous people died in the massacres, including children and the elderly, according to the non-governmental organization Association for Justice and Reconciliation.

Former military dictator Efrain Rios Montt was in 2013 sentenced to 80 years in prison for the genocide of Ixil Maya people during the civil war.

The sentence was later overturned and he died in 2018, aged 91, as a retrial was underway.

Another retired general, former head of military intelligence Manuel Callejas, was due to stand trial alongside Lucas Garcia.

But instead he will be tried behind closed doors due to mental incapacity.

Some 200,000 people died or disappeared in Guatemala's civil war, more than 80 percent of them ethnic Maya, according to United Nations figures.