An arrest warrant has been issued for ousted Burkina Faso leader Blaise Compaore over his alleged role in the 1987 murder of ex-President Thomas Sankara, judicial sources say.Mr Compaore's ally, Gen Gilbert Diendere, was recently charged in connection with the killing.
Both men have denied any wrongdoing. Mr Compaore is in exile in Ivory Coast after being forced to resign last year.
Mr Sankara, a left-wing radical, is considered a hero for many Africans.
Mr Sankara, described as "Africa's Che Guevara", was succeeded by Blaise Compaore who stayed in power for 27 years, before being ousted by street protests in 2014.
The exact circumstances of Mr Sankara's death have remained a mystery.
Remains thought to be those of Mr Sankara were exhumed earlier this year.
But a test carried out in a French laboratory found no usable DNA, reports Abdourahmane Dia of the BBC French service.
The result was handed on Monday to a judge who earlier this year ordered the exhumation of the corpse as part of an investigation mandated by the transitional government that took over from Mr Compaore.
Mr Sankara's family said recently that an autopsy has found that his body was "riddled with bullets".
During Mr Compaore's rule the investigation into the murder made little progress.