State safety officials say the crane that two construction workers were killed on last month in Winters was not certified and should not have been used.
Officials say the crane's certification had expired days before the accident.
A spokesman with the California Division of Occupational Safety and Health says such heavy equipment must be re-certified annually.
The six month investigation uncovered Disney Construction was cited for five safety violations in 2006 during work on a construction project in the South Bay. Four more safety violations were sited in 2008.
Cal-OSHA authorities temporarily suspended the $12.3 million bridge project connecting Yolo and Solano counties and shut down the equipment on the site.
An order has been placed prohibiting the use of the two cranes.