Steven Ross, the former scientific director of OceanGate, testified before a U.S. Coast Guard panel on Thursday about a malfunction that occurred on the Titan submersible just days before its fatal implosion.

The U.S. Coast Guard has released the first photo of the doomed OceanGate Titan submersible. The vessel had been on an expedition to tour the wreckage of the Titanic when it imploded shortly after losing contact with its support ship last June.

The company's former operations director, David Lochridge, testified that the Occupational Safety and Health Administration received his complaint, but did not pursue concerns about the submersible's safety.