WAXAHACHIE —The Ellis County Justice of the Peace has declared the Aug. 23 death of 6-year-old Phillip Oliver “Ollie” Wiedemann to be homicide resulting from the “toxic effects of hydrogen sulfide,” according to a report from CBS 11 DFW.

The report stated that authorities remain unclear on how the toxic chemical compound found its way into the young boy’s system.

Wiedemann’s body was discovered alongside his mother, Candace Harbin, in a parking garage in downtown Waxahachie on Friday night, Aug. 23. John Wiedemann, the boy’s father, had reported him missing at approximately 9 a.m. that morning, and an Amber Alert was issued later that afternoon. A warrant was also issued for Harbin under the charge of kidnapping.

Ollie was last seen with his mother on Aug. 22 when she picked him up from school.

Harbin and the boy’s father had an estranged relationship and shared custody of 6-year-old Ollie at the time of his death. CBS 11 DFW reported in August, however, that Harbin had “an extensive history of mental health issues” and the case was not related to “a custody battle gone wrong.”

CBS also released a statement from John Wiedemann, made shortly after the discovery of the bodies:

“Friday, August 23rd was an unspeakably tragic day for the Wiedemann family. We ask for your prayers and God’s guidance as John and his family struggle with the traumatic loss of his precious son, Phillip Oliver “Ollie” Wiedemann.

Ollie was an amazing young boy who cared about people. He always wanted to make others happy and if ever a classmate was having a tough day, he would reach out to help them. He loved swimming, Legos and superheroes but most of all he loved going to school.

Our hearts are broken and may never be whole again.

We thank the Waxahachie Police Department and other first responders who helped search for Ollie. We want to thank the Ellis County District Court for seamlessly processing the paperwork that enabled the Amber Alert system to be activated. We also want to thank the Ellis County community and all others who have sent prayers and thoughts.

Nothing can be said or done that will bring Ollie back and we ask for privacy as we grieve. As there is an ongoing investigation, we ask that further requests and comments be directed to the Waxahachie Police Department.”

Joseph Iglesias called 911 to report the location of Harbin’s white Nissan Quest minivan on the night of Aug. 23, according to CBS 11 DFW.

“If something like that would happen to my little boy, I wouldn’t know what to do,” Iglesias told CBS in August. “I pray for the family. Me and my wife haven’t been able to sleep since that event.”

Residents of Waxahachie and the surrounding area gathered on Aug. 24 and Sept. 5 for candlelight vigils to honor the memory of 6-year-old Ollie.