On Tuesday, Arizona joined more than 40 states across the U.S. to proclaim June 6 “Secure Your Load Day.” It's very personal for one Arizona family.

Exactly 11 years ago, on a hot summer day, Paul and Toby Reif’s 29-year old son Matthew drove along Hunt Highway near Ellsworth Road.

Forensic investigators were never able to pinpoint whether a deadly piece of metal flew off the back of a truck or bounced off of the roadway after another car hit it.

But, unsecured on the highway, Reif said the debris was as deadly as a bullet.

“It was 1 foot long and 4 inches wide, and a half-inch thick, and it probably weighed, I think 10 pounds, it was tiny. It came right through, he never saw it coming. It was instant,” Reif said.

He holds no contempt for the driver who lost the chunk of metal that killed his son, but Reif said he hopes the driver knows now to put small items inside the truck, tie down anything in back and cover it before getting on the road.