US and Canada start the process of determining how the Titanic-bound submersible imploded

Authorities from the U.S. and Canada have begun the process of investigating the cause of the fatal Titan submersible implosion even as they grapple with questions of who will be responsible for determining how the tragedy unfolded. The U.S. Coast Guard said Friday a formal inquiry has not yet been launched because maritime agencies are still busy searching the area where the vessel fell apart. It was not entirely clear who would have the authority to lead what is sure to be a complex investigation involving several countries. The National Transportation Safety Board said the Coast Guard will lead the investigation, but the Coast Guard has not confirmed that.