Heat exhaustion is the cause of death of a Brazilian fan who attended a concert of singer Taylor Swift in November, a forensics report obtained by The Associated Press shows.

Ana Clara Benevides, 23, passed out during Swift’s second song at the November concert in Rio de Janeiro, “Cruel Summer,” and died hours later at a local hospital. Temperatures in the city that day were at about 40 degrees Celsius.

Fans lined up for hours before the show, and many accused organisers of failing to deliver enough water supplies for the more than 60,000 attending the concert at the Nilton Santos Stadium. They said they were not allowed to take their own water into the stadium.

The report by Rio’s Forensic Medical Institute said Benevides’ heat exposure led to a cardio respiratory arrest. It also said she did not have pre-existing conditions or substance abuse that could have led to her death.

The forensics expert who analysed her body said in the document she had “serious compromise of her lungs and sudden death” due to the heat.

One of Benevides’ friends, who also attended the concert, told local media outlets in November they had been given water while waiting to enter the stadium.

Organisers T4F said in a statement the company “followed the best practices,” complied with “every demand from authorities” and “distributed thousands of bottles of water” to fans. TF4 also denied it did not allow people to bring their own water to the concert.

TF4 also said Benevides “was promptly cared for by members of a rescue team and sent (to the hospital) in an intensive-care unit ambulance.”

“In our 40 years in the business, this company had never registered a tragic episode” like Benevides’ death due to extreme heat, T4F said.

The office of Rio’s public prosecutor has opened a criminal investigation. Rio police said in a statement on Wednesday that after the forensics report is analysed “representatives of the company organising the event will be called to testify.”

Benevides’ death shook many in Brazil. She had taken her first flight to travel from the country’s centre-west region to see her favourite singer.

In a statement posted on Instagram after the death, Swift said the case had left her with a “shattered heart.”

Benevides’s father, José Weiny Machado, told news website G1 he “never doubted the cause of death was the heat.”