An Illinois father and stepmother will spend decades in prison after pleading guilty to murder in the starvation death of their 6-year-old son, who authorities said weighed just 17 pounds when he died.

The Alton Telegraph reports a judge sentenced Michael L. Roberts to 25 years and Georgena L. Roberts to 20 years during a Wednesday morning hearing.

The 43-year-olds from Jerseyville both pleaded guilty to first-degree murder in November. Two counts of endangering the life and health of a child were dropped.

Authorities have said the couple starved the boy as a form of punishment and withheld food and nourishment on a regular basis. When he died, the boy weighed about a third of what a typical 6-year-old weighs. Preliminary autopsy findings indicated the death was extreme malnourishment.