News quickly spread that Ollie might be with his mother and in danger.
Hours later, the tragic news. Both bodies were discovered in the mother's minivan atop a parking garage in Waxahachie. Investigators would later rule it a murder-suicide.
The boy's father, John Wiedemann is speaking out for the first time about the little boy he lost and the court system, he said failed them.
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"Taking it one step at a time. One hour at a time. One day at a time," Wiedemann said as he took his morning walk this fall.
He said not a moment goes by that he doesn't think about Ollie, his 6-year-old, only child.
"Legos were his deal. He was precious. He played T-ball, soccer. He was wonderful. He's the sweetest soul you would ever meet. He cared about everybody and he loved his mom."
Wiedemann said Ollie's mother, Candace Harbin, started to change when he was a toddler.
"We never argued. I could just tell she was depressed. I asked her if she had any suicidal thoughts. She said, 'Yes.' I said, 'We need to get some help.'"
When she resisted, he said, things started going downhill. The two were never legally married and the next few years became a bitter custody battle for Ollie.
"I've never been through anything like this in my life. I didn't know what to expect. As I got further into it, I felt like the system failed my son," Wiedemann said.
In 2016, Wiedemann got custody after a social study evaluator warned that Ollie's mother had clinical issues, ruling her time with Ollie needed to be supervised. But that supervision, he said was done by a nanny camera. He was told Harbin's parents would be the one monitoring the visits through the nanny cam.
But in March of this year, a second social study evaluator allowed the mother, "unsupervised" visits with Ollie.
"That's the final deal right there." Wiedemann said almost immediately, his son started to change.
"The way my son was acting, I knew something was wrong. Sunday night on August the 18, my son stood up on the couch and said, 'I'm hurting so bad and nobody is helping me,'" Wiedemann remembers.
That was one of the last times he saw Ollie.
"Thursday, I knew something. Just this bad feeling." Thursday, Ollie went home with his mother after school. He never returned to school the next day.
"8 a.m. comes and I call the school across the street and they say, 'He is not here.'"
Wiedemann said he spent all day at the police station with an investigator familiar with this case.
"I looked her straight in the face and I told her that she was going to kill him. So, they started scrambling trying to ping the phones. I was at the police station all day and they finally got the Amber Alert out," Wiedemann said.
It was at the point he said, he knew Ollie was gone.
Investigators that evening told him the news that Ollie and his mother were found dead in her minivan in a parking garage. Later, Ollie's death was ruled a homicide by toxic effects of hydrogen sulfide.
"I said goodbye to my son. I held my son for the last time and I made a promise that I would do everything that I could to make sure that this wouldn't happen to another child. That was my promise. I don't break my promises, especially to my son."
Wiedemann hopes that by speaking out, the system can change, that there can be consistency on the bench and stronger child advocacy programs put into place.
"It's a broken system. I think being a small town, they aren't equipped to supervise these kids," Wiedemann said.
He also hopes the public will look around and speak up when they see signs of child abuse.
"It's going on everywhere. So many people suffering and it needs to stop. It needs to stop," Wiedemann said.
As for his future, Wiedemann said God is guiding his steps. He's walking in faith that he'll see Ollie again in heaven. "I truly believe in God and so did my son."
Wiedemann said he's been told the courthouse in Ellis County is planning to name a room in Ollie's honor.