Instructor of Calgarian who died while diving also felt sick

The dive master who was underwater with a Calgary woman when she died in Mexico says he's not sure what went wrong, but he also felt sick and dizzy from the dive.

Ronda Cross's family claims she was overcome by carbon monoxide in her air tank

The dive master who was underwater with a Calgary woman who died when scuba diving in Mexico says he's not sure what went wrong.

Jorge Duchateau took Ronda Cross and her cousin on a dive off the coast of Cabo San Lucas on Saturday.

Cross's family believes she was overcome with carbon monoxide — and blames the company that filled the tanks.

Duchateau says he also started feeling sick about 15 minutes into the dive.

Ronda Cross died Saturday in Mexico while scuba diving. (Cross family)

Cross's cousin, Roxanne Amundson, says it was a bad experience from the start.

"I didn't feel like I was getting enough air, but the reason I surfaced was I couldn't clear my mask," she said.

Amundson says her cousin appeared fine when she and the dive master surfaced together, so she shrugged it off as being a new diver.

Cross was an experienced diver. According to her husband, Colin Cross, she had done more than 200 dives around the world.

Something was wrong

"I wasn't going to finish the dive but I knew she was down there waiting for us, so we went back down," she said.

But when they did Ronda Cross was gone.

Dechateau says it wasn't until the second time the two surfaced that he noticed something was wrong.

"I was feeling terrible," he said. 

"I was dizzy. I don't remember much, but I can tell my eyes were closing at some point and right before we reached the surface I had a pain in the chest."

Authorities are now investigating whether the trio were suffering from carbon monoxide poisoning.

Cathie McCuaig, with the Alberta Underwater Council, said a faulty air compressor could have been the problem. She said its rare, but it happens.

"The compressor is usually the cause of it, or the compressor air intake is too close to another piece of machinery that's letting off carbon monoxide fumes," she said.

Duchateau says he gets his tanks filled by a local company — and he's used the same one for the past three months. He is also certified as part of the Professional Association of Diving Instructors (PADI).