The unidentified neighbour had been charging their phones and bringing food to the children for at least a couple of weeks after the power in their apartment was cut off, a spokesperson for Harris county’s sheriff department told news website The Daily Beast on Monday.
The 15-year-old had called the police on Sunday afternoon and said that he and his siblings had been left alone by their parents in the apartment and that his nine-year-old brother had died.
Concerns have now been raised by the other neighbours about how the children were not discovered in the apartment complex earlier.
Residents who did not wish to be named told The Daily Beast that it was surprising that maintenance workers, who had been visiting the apartment complex regularly, had not noticed the remains of the child.
Some neighbours told the outlet that while the child’s mother was seen around the apartment complex, they did not know she had children.
Officials had gone to the building, about 32 kilometres away from downtown Houston, and found the three children as well as the skeletal remains of their sibling lying in the open.
Authorities said the surviving children had been living there for close to a year. They appeared malnourished and showed signs of physical injury, according to officials.
“All three were transported to a hospital to be assessed and treated for their injuries. It is believed the parents have not lived in the unit for several months,” county sheriff Ed Gonzalez said in a tweet thread.
“The older sibling was doing the best he could to take care of the others,” Mr Gonzalez had said at a Sunday press conference.
The police located the children’s mother and her boyfriend and had taken them in for questioning.
Both were, however, later released, without any explanations given by the authorities as to why they were set free.
State child welfare authorities have begun a probe, along with the one underway by law enforcement officials, and are now seeking emergency custody of the children.