OceanGate CEO Stockton Rush always planned to die at the wreck of the Titanic, according to a close friend accusing him of murdering the wealthy tourists who paid big money to ride his “mousetrap for billionaires.”

The multimillionaire engineer wanted to become part of “Titanic mythology” by designing a makeshift submersible to implode when he took it 12,500 feet to the sea floor, according to his longtime friend Karl Stanley, a fellow expert in commercial submersibles wh

“He was in fact a good engineer, and that machine did exactly what he designed it to do … He set a new standard for going out with a bang,” Stanley told author Matthew Gavin Frank for his new book, “Submersed: Wonder, Obsession and Murder in the World of Amateur Submarines.”

“Rush’s ego was so big he was willing to die and kill to be the pivotal character of this story. He wanted to go [die] at the wreck [of Titanic],” Stanley told Frank just days after the Titan implosion.

“The more high-profile, the better. He didn’t just murder four wealthy people and get paid a cool mill to do it — they are allll part of the Titanic mythology now.”

The doomed 2023 dive killed Rush along with five tourists who paid him up to $250,000 for the fatal ride.

They were French underwater explorer Paul-Henri Nargeolet, known as “Mr. Titanic,” British adventurer Hamish Harding, and two members of a prominent Pakistani family, Shahzada Dawood and his son Suleman Dawood.

Stanley claimed Rush, a Titanic fanatic, knew that the excursion was a one-way trip that once complete, would cement his name into the history books. 

“I know this is what happened,” stressed Stanley, who testified during the US Coast Guard’s inquiry into the catastrophe that Rush always planned on dying and described him as a “criminal.”

“Rush needed to compel more than just his own death, and he needed to knowingly fabricate a ‘futile’ vessel, costumed in a titanic name, as his murder weapon,” Frank wrote in his new book.

The CEO even named his Titan submersible after the fictional British ocean liner “Titan” from the 1898 novel “Futility” by Morgan Robertson — in which the massive ship sinks after smashing into an iceberg, eerily like the Titanic would in 1912 years later.

Those who worked with Rush at OceanGate were “sh–ting their pants” in the wake of the explosion, Stanley said. “But, [Rush] being a madman who manipulated them is the best narrative for them.”

Stanley was friends with Rush for more than 10 years and even joined him on one of the Titan’s test dives in 2019 — during which he recalled hearing loud cracking noises, but had his concerns brushed off by Rush.

He told Frank that he doesn’t regret going to the wreck with him in 2019.