Amnesty International has asked Chad to ensure that officers responsible for killing protesters during demonstrations in April and May are prosecuted.
The demonstrators were calling for the return pf constitutional order after President Idriss Deby Itno died of his injuries on 20 April following clashes with rebels in the north of the country.
His son, 37-year-old four star general Mahamat Idriss Deby Itno, took over, leading a military council until elections are held.
The protests which followed were banned and met with brutal force by the security forces.
Hundreds of demonstrators were arrested and dozens died.
Amnesty International and other rights organisations have in the past called for an investigation into the deaths.