Siberon will face 10 years in prison and 20 years parole for his abuse against the girl, now aged 12.
It's understood that the girl had first reported the assault in 2015, but the DNA was not sent away for testing until two years later, shortly after Siberson was being investigated for his son's death.
The baby boy, known as Donovan, was found unresponsive in his home in April, 2017.
He'd suffered head injuries and a detached cornea and tragically died in hospital the following day.
According to the ctpost, Siberon was charged with first-degree manslaughter and risk of injury to a minor.
He has pleaded not guilty but it is not yet known when he will face court for these charges.