The Maumere District Court in Sikka regency, East Nusa Tenggara (NTT), sentenced former Catholic priest Herman Jumad Masan to life after finding him guilty of killing his lover, Merry Grace, and their two infants.
Presiding judge Beslin Sihombing said the panel of judges could not hand down the death penalty sought by prosecutors.
"Let the defendant contemplate, think and reflect [on his crimes]. This is already an appropriate punishment for him," he told reporters after delivering the verdict.
Merry's relatives said they were satisfied with the verdict. One of them, Martono Duran, said the verdict was fair, appropriate and relative to Herman's crimes.
Earlier, Merry's relatives demanded the death sentence for Herman.
Agung Raka Putra Dharmana from Maumere Prosecutor's Office told The Jakarta Post that prosecutors were still deciding if they would appeal.
Herman was found guilty of premeditated murder in the slaying of Merry and the two infants, which were the offspring of an illicit relationship with Merry.
He met Merry in Hokeng in 1995 while serving as a priest. The victim was then a student at Ledalero Catholic Philosophy Institute (STFK).