(CNN) -- Valerie Wood-Harber's brother, Quinten, needed a lot of special care.
He was born with a rare chromosomal abnormality, which meant even as a teenager, he needed help doing things that most people take for granted.
Getting dressed could be a challenge. So could eating.
But Quinten was also a happy child, who loved water, hugs and the music duo Daft Punk, his sister said. He smiled and laughed about everything.
"Honestly, my biggest worry about him was that he was going to outlive the people that were able to take care of him," said Wood-Harber.
"That was my biggest fear. He was healthy."
Quinten Douglas Wood, 15, died on January 4.
A medical examiner's report lists his cause of death as acute pneumonia. The manner of death was ruled natural.
Despite the report, Wood-Harber, 28, says she has questions, and she's not alone.
Wood-Harber has started an online petition, calling for the governor to investigate schools and the Oklahoma Department of Human Services over her brother's death, which she says was caused by negligence.
More than 250,000 people have signed it.
Quinten passed away less than a month after Wood-Harber says she called DHS to report their father, who took care of Quinten and the boy's younger brother in Oklahoma City. Wood-Harber lives in Fayetteville, Arkansas.
In keeping with its policy following the death of a child when there is an open or pending referral, DHS initiated an investigation.
The department is working alongside the Oklahoma City Police Department, the Oklahoma Commission on Children and Youth, the Oklahoma Medical Examiner's Office and The Children's Hospital.
Their investigations are ongoing.
The goal is to find out exactly what happened, said Sheree Powell, director of communications and community relations at DHS.
Who knew what and when? And what, if anything, could have been done to prevent Quinten's death?
"I think the biggest thing we would like to emphasize right now is just how heartbreaking this whole situation is and that we're working very, very diligently to try to find justice for this boy," Powell said.
When his son was born, Michael Wood says that doctors thought he wouldn't live to be a year old.
Unlike his daughter, he recalled the various health problems his son suffered.
Wood, 47, said Quinten had so many ear infections that antibiotics rarely worked. He had been hospitalized at least nine times with pneumonia, and each time took its toll, he said.
A single working dad, Wood needed help to care for his disabled son. He said he went to DHS three times, starting in 2010, to ask for it.
"They bounced me to another department, and they said well, somebody will come out. And nobody ever came out," Wood said. "I finally said, forget it, I'll do it on my own."
"I'm not real big on every time I have a problem, go to somebody else to fix it," he said.
Powell, with DHS, declined to comment on whether Wood had ever approached the department and if so, what happened. That sort of information, if it exists, would be included in a report DHS plans to issue at the end of its investigation.
Without help at home, the responsibilities of feeding and changing Quinten fell to his other son when Wood was at work.
The brothers were only a year apart and best friends. They were together when Quinten died.
Their father left work early that day because he felt under the weather. Already sick, Quinten's brother was home from school.
"I was going to take both of them to the doctor that afternoon," Wood said.
Quinten stopped breathing before he got the chance.
His father started CPR and told his other son to call 911. Quinten was transported to The Children's Hospital, where he was pronounced dead shortly after arrival.
"As a parent, no matter how your kid dies, you feel guilt," said Wood.
"Would he have been alive if I'd taken him to the doctor the day before? Probably, maybe not, I don't know. People die of pneumonia in the hospital."
He said he thinks about things he could have done differently. He wishes he'd spent every second with Quinten that he could.
But sometimes, life gives you a bad hand, and there's nothing you can do.
"There are some people that when they're hurting, they have to put blame somewhere. Personally, I was raised a Christian, and personally I put the blame on God," said Wood.
He lashed out at his daughter and others who say he wasn't a good father.
"If I didn't care properly for Quinten, he wouldn't have lived 15 years, especially when we were told that he wouldn't live to see a year."
Wood-Harber says she 100% believes that her brother would be alive if her father had taken better care of Quinten. But, in her mind, others are responsible for his death as well.
Parents might fail, but that's why there are agencies in place to pick up the slack.
Specifically, she said she told teachers and administrators at the boys' schools -- Jarman Middle School and Midwest City High -- to be on the lookout for signs of potential abuse or neglect. She thinks they failed to notice Quinten lost a substantial amount of weight.
"They're called mandatory reporters for a reason. If you even suspect something is going on, you're supposed to report it," said Wood-Harber.
Stacey Boyer, director of community relations and records management at Mid-Del Schools, which includes both of the boys' schools, declined to comment on the case, citing privacy laws.
She said no one from the Wood family has contacted the Mid-Del Board of Education.
Besides the schools, Wood-Harber blames DHS and the police.
She says she called to report her father to DHS on December 17. A worker went to interview Quinten and his brother at their schools almost immediately, she said.
The worker promised to make a home visit the next day, but never showed up, and stopped returning her calls, according to Wood-Harber, who says she also reached out to police.
The Oklahoma City Police Department received a report from an anonymous caller on December 17, requesting that officers check on Quinten and his brother, said Sgt. Jennifer Wardlow.
Officers checked the home, but there was no answer at the door.
No report was generated.
Far away and frustrated, Wood-Harber considered at one point just going to Oklahoma City and taking the boys.
"Of course if I could trade a pair of handcuffs, and sitting in a jail cell serving time for kidnapping, for my brother being alive, I would do it in a heartbeat. But at the same time, I know that with the resources and the information that I had at my disposal, I did everything that I could.
"I relied on the system to work, and that's just the problem. The system, it doesn't work. It's very much broken," she said.
Wood-Harber started a petition at Change.org, which has so far collected more than 250,000 signatures.
In it, she calls for the governor of Oklahoma to investigate DHS and the schools. She hopes it will help ensure that what happened to Quinten won't happen to another child.
"This isn't just a cautionary tale. We could actually change things and prevent this from happening on a larger scale," she said.
Alex Weintz, a spokesman for Oklahoma Gov. Mary Fallin, told CNN that her office was aware of the petition and monitoring its progress. The governor's staff has requested more information from DHS.
In the meantime, Quinten's sister says she'll continue speaking out about her brother, and on behalf of other children.
"That's the only way that I can make sense of it. Maybe if what happened to Quinten can save somebody else's life, then there'll be a little bit of justice in this world," she said.
CNN's Kevin Conlon contributed to this report.