The government’s chief investigation into last year’s Deepwater Horizon disaster will not be complete by a July 27 deadline, officials confirmed Friday.

The probe by the U.S. Coast Guard and the Bureau of Ocean Energy Management, Regulation and Enforcement has already received two extensions, partly because of delays in testing emergency equipment that failed to stop the Gulf oil spill. In February, the government said it was aiming to issue the report by July 27.

Joint investigation team members now are putting the final touches on a report summarizing their conclusions about what led to the lethal explosion of the Deepwater Horizon rig in April 2010.