Robert Shook, 38, was shot in the driveway of the Rock Hill, South Carolina home where he had been working, the York County sheriff said, and he died from his wounds on Saturday.
The gunman, whom officials identified as Phillip Adams, 32, opened fire at the home of doctor Robert Lesslie, killing Lesslie, 70, his wife Barbara Lesslie, 69, two of their grandchildren, 9-year-old Adah Lesslie and 5-year-old Noah Lesslie, and James Lewis, 38, another air conditioning technician, the county sheriff's office said.
"We are all heart broken," the men's employer GSM Services posted on Facebook on Saturday.
Adams, who left the National Football League more than five years ago, died from a single gunshot to the head at his home a short distance from the murder scene. Investigators have not identified a motive for the shootings.
"We have probably more questions than you do right now," York County Sheriff Kevin Tolson told reporters on Thursday.
There was no indication that Adams had any relationship with Lesslie or his family, Tolson said.
The gunman's father, Alonzo Adams, suggested the shooting outburst was the result of injuries his son sustained during his football career, in which he played as a defensive back with five teams, finishing with the Atlanta Falcons in 2015.
"I think the football messed him up," he told WCNC-TV in Charlotte, North Carolina.
Asked to comment, an NFL spokesman said, "Our hearts go out to the families and friends of the victims of this devastating tragedy."
