Misdemeanor charges filed against four people in connection to the death of a 13-year-old boy at a mini-fairground in Elliniko, southern Athens, on Sunday, were upgraded to felonies on Tuesday, after new evidence emerged during the ongoing investigation.

The four defendants, the fairground’s owner, an Italian man who rented equipment and two Bangladeshi fairground employees were expected to face a prosecutor on Friday.

The boy and his 9-year-old sister, who sustained serious injuries in the same incident, had been in helium-filled cylinders, known as water rollers, on a pool in the playground in Elliniko when a strong gust of wind blew them about 30 meters.