Jimmy Somo of Gomena village pleaded guilty before the Lae National Court to attacking Kove Gomena, which led to his death.
Gomena died on 5 March 2016 from injuries inflicted by his biological brother, Sep Gomena and Somo.
The deceased that day armed himself with two bush knives and was acting violently. In the course of this, he was said to have cut the baby who was then sleeping in a bilum.
In retaliation, men from the community charged at the deceased, who dropped the bush knife and surrendered to them.