was it an elite travel adventure or reckless experiment that challenged the laws of engineering? difficult questions being asked tonight as officials and deep sea diving experts speak out on the deaths of five people on a visit to the titanic aboard a vessel built with uncertified technology. tonight oceangate, the company behind that deadly submersible dive, says it is closing indefinitely after the apparent implosion that killed among others oceangate s founder. meanwhile, we are now getting the first information on how the international investigation might take shape as questions continue to focus on the design of the mini-sub and whether it should have been diving to such depths. totom cocostello hasas late new information on the search for answers. reporter: tonight canada s transportation safety board has launched an investigation into titan s apparent implosion on sunday. the u.s. coast guard and ntsb expected to join soon. outside experts are