The siblings of a malnourished 12-year-old boy in Utah told deputies that their brother had been locked inside a filthy bathroom for at least one year, possibly two, authorities said.

“The child looked like he was the victim of a concentration camp from World War II,” one official said.

Washington County Sheriff's Office Lt. David Crouse said Tuesday the children said they did not speak to their brother through the door in six months.

He declined to give their ages, but said one was old enough to understand things.

The boy was found Sunday at his home in the small southeastern Utah city of Toquerville near the state line with Arizona. Crouse says investigators have discovered the boy was likely kept in the dark.

They found 3 square feet of duct tape mounted on the light switch so it could not be turned on. He says a doctor who treated the boy says it is the worst case of malnourishment he had ever seen.

Crouse says the boy was unable to stand on his own and weighed 30 pounds. He's expected to stay in the hospital for several weeks to recover.

Crouse says seeing the pictures of the gaunt boy and the feces-filled bathroom was horrible.

Brandy Jaynes, 36, was charged with second-degree felony child abuse after the boy’s father found him emaciated in his Tocqueville, Utah, home.

Her lawyer did not immediately return a call for comment.

The Associated Press contributed to this report