"Quinten isn't breathing," her 14-year-old brother Cameron told her, referring to their 15-year-old brother, who suffered from Chromosome Ring 9, a rare disorder that made it difficult for him to walk, talk and eat on his own.
"I can't wake him up," Cameron told her on Jan. 4, 2013. "Come here now."
By the time she got there – making the four-hour drive from Fayetteville, Arkansas, where she lived, to Oklahoma City, where they lived, in just under two hours – Quinten was dead.
Wood-Harber, who had filed a complaint with the state Office of Disability Concerns three weeks prior accusing their father, Michael Wood, of abusing Cameron, immediately suspected the worst.
Despite calling the agency 22 times, no one from the agency visited the home. Though the medical examiner later said the cause of Quinten's death was pneumonia, Wood-Harber knew it was neglect.
So in the throes of her grief, as she put her hand on his chest, ran her fingers through his hair and sang him his favorite song, "Twinkle Twinkle Little Star," she made a vow.
"I won't let Dad get away with this," Wood-Harber, now 29, whispered in his ear. "I will get justice. I promise. I'm so sorry."
She kept her word.
Justice for QuintenAfter filing a Change.org petition calling for an investigation into Quinten's death (which got 500,000 signatures) and launching her own vigorous online campaign (complete with photos documenting the neglect and abuse), their father, Michael Wood, 48, was charged with two felony counts of child neglect – one for each of his boys – in March.
In addition, two child welfare workers – supervisor Paul Kim Myers, 58, and worker Rachelle Qualls, 25, – were charged with willfully neglecting their duty.
Qualls pleaded guilty and was given a one-year suspended jail sentence and one year probation, her attorney, Irven Box, tells PEOPLE.
"She pled guilty because she didn't fulfill her duties but she was overworked," he says, "and we believe the system is overloaded."
The other defense attorneys could not be reached for comment.
The campaign also resulted in the passage of The Quinten Douglas Wood Act of 2014, legislation that instructs Oklahoma DHS workers to take a disabled child's inability to communicate into account when investigating child abuse and neglect.
"If someone didn’t listen to her, Valerie went to the next person until she got heard," Kathryn Brewer, advocate general of the Oklahoma Department of Human Services, tells PEOPLE.
"It's a honor to know her and know much she fought for him," she says.
Wood-Harber met her biological father for the first time on March 1, 2005, and her three half-brothers a few days later.
Three days after she met the boys, he asked her if she could watch Quinten and Cameron, the oldest two, for one or two months while he went back to Kuwait as a military contractor.
Those couple of months soon turned into years.
"I went from being their sister to their mother," she says. "They became my kids."
The brothers also became best friends.
"They were each others' halves," Wood-Harber says. "Where one went, the other followed."
Despite Quinten’s physical limitations, he was happy and healthy.
"He was always laughing and had the most infectious giggle you have ever heard," she says.
Their father returned in late 2008 and, while the house was never very tidy when she visited, it wasn't until mid-December 2013 that Cameron called her with some alarming news.
"He told me our father was beating him and forcing him to cook, clean and care for Quinten," she says.
She told Cameron help was on the way and immediately called child services.
"Cameron would hold Quinten in his arms and say that someone was coming to save them," she says.
No one did.
When he died, Quinten weighed just 54 lbs. – 16 lbs. less than he did during his last doctor's visit on March 7, 2011.
Today, Wood-Harber has legal guardianship of Cameron and is studying psychology and criminal justice at a local university, all while working full time as an at-home aide, so she can become an advocate for people with developmental disabilities.
Though she'd have plenty of ammunition, she does not plan on filing a lawsuit against the state.
"I don’t want money or anything from his death," she says. "I just don’t want this to happen to any other child."
Know a hero? Send suggestions to firstname.lastname@example.org. For more inspiring stories, read the latest issue of PEOPLE magazine