A flawed demolition plan contributed to the collapse of a highway overpass that killed a construction worker in Cincinnati, Ohio last month, the contractor for the construction project said.

The preliminary findings from an independent engineering firm have been sent to federal and state investigators, according to a statement Kokosing Construction Co. released Saturday
“Our engineering firm has told us that it wouldn't work the way it was,” Brian Burgett, chief executive officer of Columbus-based Koko­sing, told the Cincinnati Enquirer.

The collapse during demolition work to remove an Interstate 75 ramp bridge just north of downtown Cincinnati killed Brandon Carl on Jan. 19. The parents of the 35-year-old father of four from Augusta, Ky., filed a lawsuit a week ago against Ohio’s Department of Transportation, charging negligence and carelessness.

A Michigan truck driver traveling on I-75 also was injured in the late-night collapse when the front of his vehicle was crushed by the impact with the concrete and debris.

Kokosing said earlier this month that the demolition plan was changed just hours before the structure collapsed, but the company now thinks the plan was flawed from the beginning.