PITTSBURGH — A 6-year-old Pennsylvania boy whose mother allegedly held him underwater in a bathtub died Saturday, four days after his younger brother drowned, the Allegheny County Medical Examiner’s Office confirmed.

The boy, Daniel Schlemmer, had been declared brain dead after authorities say he and his 3-year-old brother, Luke, were submerged underwater by their mother at their McCandless home Tuesday.

Forty-year-old Laurel Michelle Schlemmer is being held in the Allegheny County Jail without bond on criminal homicide and other charges in the death of her younger child. With Daniel’s death, the charges against her are expected to be amended.

County detectives say the mother told them she tried to drown both boys by sitting on them in the tub after a third son left for school. They say she told investigators she heard “crazy voices” telling her to push the boys underwater.

Daniel had been on life support at a Pittsburgh hospital, according to the prosecutor’s office.

Schlemmer didn’t speak during a short video conference earlier this week, and her attorney, Michael Machen, declined to comment afterward.

Machen got court permission to have Schlemmer evaluated by a psychiatrist hired by her family. She appeared in a special vest that is designed to prevent inmates from tearing off their clothes and is on suicide watch at the jail.