Home Depot, the Atlanta-based building supply giant, faces a wrongful death lawsuit over eight people dying inside its store when a 200-mph tornado carved a path estimated as a mile wide and six miles long through Joplin, Mo., in 2011.

The storm lifted the steel-truss roof from Home Depot, at 3110 E. 20th St., causing 63 concrete tilt-up building panels to topple.

Russell T. Howard, a 29-year-old electrician, his 5-year-old daughter, Harli, and his 19-month-old son, Hayze, were crushed to death.

On May 23, Howard's widow filed in Jasper County Circuit Court a wrongful death suit for unspecified damages. In July, the case was moved to the U.S. District Court of Western Missouri.

The legal action follows a National Institute of Standards and Technology report on the event, released earlier this year. The document notes that the store's toppled 1-ft-thick panels, weighing up to 100,000 lb, were secured by only friction footings. By contrast, nine building panels near the loading dock remained standing. They featured more robust mechanical connections to the strip footings.

"Panels performed very well" and collapsed only after the roof failed "due to a lack of bracing," says the Tilt-Wall Concrete Association, Vernon, Iowa, who also investigated the site.

The lawsuit claims the defendants, which include Home Depot and related entities, along with St. Louis-based architect- engineer Casco Diversified Corp., failed to build an adequate roof system with appropriate roof-to-wall connections, among other allegations.

Home Depot and Casco have denied all allegations. Defense lawyers characterize the tornado as an "act of God.''

The suit also comes more than 13 years after the building's completion, placing it past Missouri's statute of limitation.