The boss of the Titan submersible repeatedly shrugged off safety concerns over the doomed vessel, according to reports of newly unearthed emails.
OceanGate CEO Stockton Rush is said to have ignored warnings from leading deep sea exploration specialist Rob McCallum that he was potentially putting his clients at risk.
The development came the Transportation Safety Board of Canada said an investigation is set to take place as a team of its investigators were deployed to St John’s to “gather information, conduct interviews and assess the occurrence”.
Mr McCallum urged Rush - who perished on the Titan along with four other men in Sunday’s “catastrophic implosion” - to stop using the sub until an independent body assessed it, BBC News reported.
The broadcaster said it had seen messages where McCallum told Mr Rush that he was potentially putting his clients at risk and asked him to halt operations until it had been classified by an independent body.
Mr Rush allegedly responded that he was “tired of industry players who try to use a safety argument to stop innovation”.
The tense exchange ended when OceanGate’s lawyers threatened legal action, Mr McCallum claimed.
He wrote to the OceanGate boss in March 2018: “I think you are potentially placing yourself and your clients in a dangerous dynamic.
“In your race to [the] Titanic you are mirroring that famous catch cry: ‘She is unsinkable’”.
Mr Rush expresses frustration with the criticism of Titan’s safety measures.
He wrote: “We have heard the baseless cries of ‘you are going to kill someone’ way too often. I take this as a serious personal insult.”
OceanGate did not comment when approached for comment by the Standard.
Mr McCallum told the BBC he repeatedly urged the company to seek certification for the Titan before using it for commercial tours, which he says never happened.
Tributes have since been paid to the Titan’s passengers and pilot, with the families of Shahzada Dawood and his son Suleman, from south west London, and British billionaire Hamish Harding describing them as “beloved” and “dedicated”.
OceanGate’s chief executive Mr Rush and French national Paul-Henri Nargeolet were also confirmed to have died in the incident 1,600ft from the wreck of the ocean liner which sank in 1912 off the coast of Canada.
In a short statement confirming the investigation, the TSB said: “The TSB is launching an investigation into the fatal occurrence involving the Canadian-flagged vessel Polar Prince and the privately operated submersible Titan.
“In accordance with the Canadian Transportation Accident Investigation and Safety Board Act and international agreements, the TSB… will conduct a safety investigation regarding the circumstances of this operation conducted by the Canadian-flagged vessel Polar Prince.
“A team of TSB investigators is travelling to St John’s, Newfoundland and Labrador to gather information, conduct interviews and assess the occurrence.
“In the coming days, we will co-ordinate our activities with other agencies involved.”
The TSB will not determine civil or criminal liability and conducts investigations for “the advancement of transportation safety”.
After the catastrophic implosion of the vessel, the other co-founder of OceanGate, Guillermo Sohnlein, defended the firm – describing regulations surrounding visits to the Titanic wreckage as “tricky to navigate”.
On Friday, five red roses were left in St John’s harbour in memory of the pilot and four passengers, with each displaying a message saying “RIP” followed by their name.
The submersible lost contact with the tour operator an hour and 45 minutes into the two-hour descent to the wreckage, with the vessel reported missing eight hours after communication was lost.
In the days that followed the report that Titan had gone missing, the US Coast Guard said the vessel had a depleting oxygen supply that was expected to run out on Thursday.
A report from The Wall Street Journal said the US navy had detected a sound in the search area for the submersible on Sunday that was consistent with an implosion.
The Associated Press, citing a senior military official, reported that the navy passed on the information to the Coast Guard, which continued its search because the data was not considered by the navy to be definitive.
