The Calgary pastor originally accused of murdering his infant son will now go to trial on the lesser charge of manslaughter.

Three-month-old Cyrus Nel died under suspicious circumstances in 2015. His father, Daniel Nel, 31, was charged with second-degree murder nearly two years later.

On Friday, defence lawyer Chris Archer and prosecutor Shane Parker agreed Nel would be tried for manslaughter instead of murder.

No reasons were given.

Three-month-old Cyrus Nel died in 2015. His organs were donated, according to the baby's family. (Calgary Police Service)

On Aug.21, 2015, someone in the baby's Taradale home called 911. When first responders arrived, they found Cyrus in medical distress. He died in hospital a day later.

After a lengthy investigation that involved consulting pediatric specialists, Nel was charged in May 2017.

Nel was an associate pastor at the Rockyview Alliance Church in Pineridge. He was put on administrative leave just before the charge was laid.

Police won't say how the boy died. Nel is free on bail.

A three-week jury trial will be booked next month.