About a year ago I read an article about him in Inc. Magazine and later profiled on CNBC, seemed like a class act.

Ken Hendricks, owner of ABC Supply and self-made billionaire, died this morning at Rockford Memorial Hospital, Winnebago County Coroner Sue Fiduccia said. Hendricks, 66, fell in his Janesville home shortly after 10 p.m. Thursday, according to the Rock County Sheriff’s Department.

Hendricks and his wife, Diane, just came home from a party and he went to check on new construction above their garage, according to the Sheriff’s Department report. She found him lying unconscious on the concrete garage floor.

The Sheriff’s Department report said it looked like an accidental fall from the second floor. He suffered head injuries from the fall. Hendricks was taken to Beloit Memorial Hospital and later transferred to Rockford Memorial Hospital. He died at 4:48 a.m., Fiduccia said. An autopsy is scheduled for today.

Representatives of his companies haven’t commented.

He was the 249th richest person in the world, Forbes magazine reported in March, worth an estimated $3.5 billion. His wealth had grown from $1.5 billion in 2005 and $2.6 billion in 2006, Forbes said.

He built ABC Supply, a building supply distributor, from the ground up and also owns Hendricks Development Group and Corporate Contractors Inc. He is survived by his wife and seven children.