The Brazilian male model who died after collapsing on the catwalk during Sao Paulo Fashion Week may have been suffering from an undiagnosed illness since birth, according to a report.

Tales Soares’ agent at the MGT Base agency, Rogério Campaneli, told Brazil’s FocusOn News that doctors are looking into what caused the model’s death.

“Doctors suspect that Tales might have had a congenital problem,” Campaneli said, according to The Sun. “From videos, they believe he died on the catwalk.”

Shocked fashionistas rushed from their seats when the 26-year-old seemingly tripped over his shoelaces on the runway for fashion label Ocksa on Saturday. Some attendees at first believed the tumble was part of the show.

“It was all so fast,” Campaneli said. “He kissed a friend behind the scenes who was following him, walked out confidently as usual, then suddenly stumbled, lost his footing and fell.”

The catwalker ate vegetarian and didn’t use illegal substances, his agency said. His sister, Gabrielle Gomes, told Brazilian media that he had regular medical checkups and she was unaware of any health problems.

“Me and my mother (Heloisa) spoke to Tales by video call before the parade and he said he was well and said he had just finished eating a carrot,” she told G1 Globo.

“We’re very scared and devastated by what happened. He was very healthy, ate healthily and exercised every day. He did crossfit and yoga.”

Soares’ cause of death is being investigated.