Ashley Elizabeth Catron and Frederick Anthony Frink faced aggravated child abuse charges in the death of Hendrix Frink.
Huntsville police officers testified that the couple's two boys were severely malnourished.
Hendrix Frink weighed 13 pounds when he died, prosecutor Tim Douthit said.
Frink's 4-year-old brother survived but weighed just 15 pounds, investigators added. It was not clear when they had discovered the condition of the boys in the home.
Catron told investigators she gave the children nutritional drinks to "revive" them rather than take them to doctors last year, WAAY reported.
One investigator said the home smelled of urine, while the boys' cribs were soiled with blood and feces.
The couple filed for bankruptcy after accruing tens of thousands of dollars in medical bills.