DENVER -- A Denver couple were advised Wednesday morning that they were being held for investigation of first-degree murder in the death of 7-year-old Chandler Ashton Grafner, who lived in their home.

Sources at the boy's former elementary school confirm there were concerns about his well-being for some time and that those concerns were well documented.

Police said the boy appeared to be suffering from severe malnutrition. There are reports the boy weighed only 30 pounds and was found by police suffering from cardiac arrest in a locked closet.

Police said they were called to the southeast Denver apartment of 26-year-old Jon Phillips and 21-year-old Sarah Berry Sunday afternoon on a report of a child in cardiac arrest.

The boy was taken to Swedish Medical Center and was pronounced dead.

Phillips and Berry are also facing a charge of knowing and reckless child abuse resulting in death. They are being held without bond.

Neither Phillips nor Berry are Chandler's biological parents. A younger boy, Dominick Phillips, was also taken from the home and placed in foster care. Dominick is reportedly the biological son of Phillips. Dominick and Chandler share the same mother.

Both boys were taken from their mother because of her drug problem and placed in Phillips' custody, their maternal grandmother told 7NEWS. She said that she fought for custody for both boys but lost.

"I didn't want him (Phillips) to have them. I just didn't have a good feeling about it. And I told the social worker, but she said there's nothing she could do about a 'bad feeling,'" said Chandler's maternal grandmother, Sandra Younger.

Younger said she had guardianship of both Chandler and Dominick from March 2006 to May 2006. Younger said she lost custody of the children because Jefferson County Social Services found her unfit to care for the children. Younger said that decision was based partially on her health, just after she found a lump in her breast.

"(Social Services) also said that because the boys were sleeping on a large couch in my living room, and didn't have twin beds in a room of their own, that I was not a good candidate," said Younger.

Younger said the boys were in good hands with her.

"They were loved, and they were safe. They were well taken care of here. They were well-fed. You can ask any of the neighbors. They were happy with virtually no needs and no wants," said Younger.

Younger said Chandler loved baseball and golf, and she lovingly described him as having beautiful blue eyes, big curly eyelashes and soft brown hair.

"He was like the most beautiful day, like today. And that was his personality," she said.

An autopsy was performed, but the cause and manner of the boy's death are pending further tests, Chief Deputy Coroner Michelle Weiss-Samaras said.

Jefferson County Social Services confirmed its involvement in the case but declined to comment further. A representative told 7NEWS it is a tragic case, and it is cooperating with Denver as the investigating agency.

Neighbors said Phillips and Berry kept to themselves and that from the day they moved in, they put blankets over the windows and kept strange hours.

"They were up at night, all the time," said a neighbor named Vahid, who wanted to go by his first name only.

His sister, Sousan, visits often and said she noticed the boy and his younger brother were small, but she didn't realize he was 7 years old.

"They were very short and tiny -- very skinny," she said. "They seemed tired. That's the only thing I noticed, because usually kids are very welcoming. They say 'Hi,' or wave or say something, exchange words. They never did anything."

But other neighbors said they never saw anything alarming.

"They looked like normal, healthy boys, obeying their father," said Chrisandra Lundgren, who lives across the hall. "I did not hear them yelling or being disciplined in any way."