A couple kept their 5-year-old son locked in a cupboard wearing only a nappy, Texas police have said.
The severely malnourished child was found bruised and with protruding bones after Harris County officers were called to a disturbance in the 21500 block of Castlemont, in Spring, Houston, on Thursday, KRPC-TV reported.
Upon arrival, police found Bradley Bleimeyer, 24, arguing with his 16-year-old stepson. The teenager told the authorities that his father and stepmother were neglecting his younger stepbrother and keeping him locked in a cupboard.
Police entered the house and found a tiny room with a lock under the stairs. But the stepmother, 33-year-old Tammi Bleimeyer, had left the house with the child before officers arrived.
Ms Bleimeyer was tracked down at a motel in Humble on Friday via her mobile phone and the boy was taken to Texas Children's Hospital.
Investigators released images of the tiny, blonde-haired child, which show his protruding shoulder blades, ribs and spine.
"He was severely undernourished - bones sticking out, bumps, bruises. His skin was coming off on his back. It's a horrific, horrific situation," Harris County Constable Precinct 4 Assistant Chief Mark Herman told KHOU-TV.
Mr and Ms Bleimeyer were arrested Friday on a charge of endangering a child. Ms Bleimeyer was released on a bond of $2,000 (£1,200) and Mr Bleimeyer, who was already out on bail for a burglary arrest, was held without bond.
The child remains hospitalised. Officials said the Children's Protective Services (CPS) is requesting emergency custody of him.