A Chilean lawyer wants charges brought against the father of the conservative presidential candidate for the murder of the father of her rival.
Gen Alberto Bachelet, father of centre-left candidate Michelle Bachelet, was tortured to death in 1974.
He died in a military facility directed by the father of centre-right candidate Evelyn Matthei, Gen Fernando Matthei.
Human rights lawyer Eduardo Contreras says new evidence shows that Gen Matthei knew about his death.
General Alberto Bachelet had been accused of state treason after refusing to join the military coup, led by General Augusto Pinochet, in 1973.
He died in a prison months later as a consequence of torture injuries.
This is the second time Mr Contreras, who represents families of political victims, has tried to prosecute Gen Matthei for the murder of Gen Bachelet.
However, Ms Bachelet has said she did not ask Mr Contreras to represent her.
'More than clear'
The lawyer says the testimonies given last month by two former officers compared with statements from Gen Matthei "make it more than clear" that he knew what was going on in the Air War Academy.
"He even took his time to classify the prisoners that should be questioned," Mr Contreras said.
But Gen Matthei's defence denies the accusations and says he had been given the post shortly before the events and was not there when the torture happened.
Ms Matthei, a former labour minister, has suggested that the move may be politically motivated.
"Everybody knows that they were friends and everybody knows that my father held a title given to him as director of the Air War Academy," the governing alliance candidate said.
The 88-year old retired general has not spoken publicly about the case and is hardly ever seen in public.
Evelyn Matthei replaced Pablo Longueira as presidential candidate for the centre-right after he resigned on grounds of depression.
An experienced politician, she is known for her outspoken rhetoric.
But her left-wing rival Michelle Bachelet is widely seen as the favourite, according to opinion polls.
The vote takes place on 17 November. A runoff will be held on 15 December if neither candidate obtains more than 50% of the vote.