Broken Arrow, OK  – A grieving mom thought her nine-year-old son drowned on Lake Eufaula, only to learn he actually passed out from carbon monoxide.

Cassi Free said when she was told her son died from drowning, she knew there had to be more to the story. After getting the autopsy results, she learned he had a deadly amount of carbon monoxide in his system that was emitted from the back of their boat.

Free said her nine-year-old son Andy was the kind of kid everyone loved.

“He wants to play, he wants to know people and make friends,” Free said.

He was kind, sweet, and adventurous, ready to try anything new.

“He was who he was he was proud of it.”

One of Andy’s favorite things to do was swim and play on the lake. Free took her family to Lake Eufaula in June to do just that.

“We let the kids go tubing, we went wakeboarding and wake surfing,” she said.

Free said the day went great, but when they were about to dock and go home, she said Andy was laying on the edge of their wakeboard boat. The boat rocked and Andy went into the water.

“He had fallen, and it was one of those situations like I guess he doesn’t want to help clean up,” she said.

She soon realized the worst.

“Andy was gone. He literally sat there suffering for what amounts to brain death before he fell into the lake,” she said.

The medical examiner’s office said Andy’s Carbon monoxide level was 72%, meaning 72% of his blood could no longer carry oxygen.

Free’s two older sons had to be treated for carbon monoxide too. She said the exhaust from the engine and idling at low speeds likely created the poisonous gas. She had no idea this was even possible.

“It took losing Andy to realize there’s a bigger problem that people just don’t know about,” Free said.

Free said she misses her son every second.

“Andy had a purpose. I believe God had a purpose for him,” she said.

Cassi said her family is purchasing a ranch in Andy’s honor and they plan to use that ranch to help other dealing with tragedies, after she gets her masters in grief counseling.

She said they will have animals like llamas on the ranch, Andy’s favorite, and trees in honor of loved ones that passed away.

For more information about carbon monoxide poisoning, visit the CDC website here.