Jury selection began in Riverhead for the murder trial of 8-year-old Thomas Valva on Wednesday.
Michael Valva, 43, and his ex-fiancé Angela Pollina pleaded not guilty to murder and multiple counts of endangering the welfare of a child.
Valva's son died of hypothermia back in January 2020 after the couple allegedly forced him to sleep on the unheated floor of their garage at their Center Moriches home.
Prosecutors say the two are responsible for the death.
Two juries will be selected because the two defendants - who will stand trial together - are blaming each other for the alleged crimes.
Though jury selection began Wednesday, it is estimated that the entire process will take about a month.
According to the judge presiding over the case, the trial to follow could take another three months.
Valva and Pollina have been held behind bars without bail since their arrest.
If convicted, they will receive 25 years to life in prison.