Franklin police said Anna admitted to "punishing" the child and putting him in a tub of hot water which caused burns to his legs.
A four-year-old boy in the US state of Ohio died after his stepmother allegedly put his legs in scalding hot water as a punishment. Anna Ritchie, 25, put her stepson Austin Derreck Cooper's legs in hot water in a bathtub before sending him to bed at their home in Franklin, Ohio, police said.
Franklin police said Anna admitted to "punishing" the child and putting him in a tub of hot water which caused burns to his legs.
The boy was put to bed early and found not breathing the next morning.
Police said they responded to a call from Boulder Drive in Franklin on Wednesday when the child was found unresponsive.
He was rushed to Atrium Hospital, where he was declared dead. His death was ruled a homicide.
"There's nothing a 4-year-old could do to deserve a punishment like this," said Franklin Police Chief Russ Whitman was quoted as saying by WLWT-TV.
"Our officers, our detectives and myself, we all have kids and some of us have grandkids now. Our hearts and prayers go out to the child's family. Nobody should have to go through something like this," he said.
Police said the child's father was in the apartment at the time, but investigators are still trying to figure out if he was involved.
Neighbours said they are horrified by the allegations.
"It's heartbreaking. I can't believe that baby lost its life. It's just disturbing how somebody could actually hurt a 4-year-old like that, let alone any child and to just do it and be OK while they're doing it and to know that baby is just screaming for help and there was nobody there to help him," a neighbour said.
Anna had been charged with child endangering and is being held in Warren County jail on a USD 100,000 bond. With the homicide ruling, additional charges are likely, and her bond was raised to USD 350,000.