A man who was injured April 11 while burning leaves and debris in south-central Minnesota has died, according to the Hennepin County medical examiner’s office.

Richard E. Martinka, 73, who uses a wheelchair, was burning the material in rural Sleepy Eye when his wheelchair tipped over, causing him to fall into the debris, according to the Brown County Sheriff’s Office. He was airlifted to Hennepin County Medical Center in Minneapolis for treatment of severe burns.

Martinka died of complications from his injuries Thursday night in the hospital, according to the medical examiner.

The medical examiner and Brown County officials continue to investigate his death.