Kevin O'Donnell, David's youngest brother, spoke with ABC7 on Friday morning, saying he was an amazing role model, the hardest worker and someone he always admired.
"I wouldn't want anyone to go through this. I wouldn't wish this upon my worst enemy," Kevin said.
Kevin is taking life an hour at a time on Friday after his brother, David, fell eight stories to his death while working on the new University of Chicago Cancer Pavilion.
"This is just unimaginable what's happened to us. It's devastating. My parents are horribly crushed by this," Kevin said.
ABC7 spoke with Kevin in south suburban Oak Forest, where David was born and raised.
"Hardest working guy I've ever known. He was great to look up to just seeing him. He went to work every day. He worked his butt off, and I am just so proud of him," Kevin said.
Authorities say David and another worker fell from a scaffold while winds were gusting at upwards of 40 mph.
David was pronounced dead on scene while the other worker was rushed to the hospital with critical injuries.
Kevin says he found out about what happened moments after getting home from work.
"I walked in to find out from my mother that my brother passed away," Kevin said.
David's father did not want to speak on camera, but says his son worked for him as a technical engineer at his company, Hi-Tech Stake Out.
In a statement, David's father said, "My son was a good person and a great man. I loved him dearly, so many people do... He was supposed to be safe at work, and now, my son is never coming home again."
As Kevin honors his brother, he is left remembering the impact David had on him during his short life.
"He was the best big brother ever. He was a great role model. He was a hard worker. He was very loving to all his friends and family," Kevin said.
Back at the University of Chicago Medical Center, the Occupational Safety and Health Administration says it has opened an inspection with the company New Horizon Steel, which employed the injured worker, but not David.
OSHA says New Horizon Steel has no previous OSHA history, and the general contractor, Turner Construction, has no Illinois violations over the past five years.