She didn’t initially understand what it meant that the Titan submersible had lost contact with the ship an hour and 45 minutes into its voyage, Dawood told the BBC Monday. It would be four more days before she would learn the fate of her husband Shahzada Dawood and son Suleman Dawood, when authorities announced Thursday the vessel carrying five people had imploded and there were no survivors.

“We all thought they are just going to come up,” she said. “That shock was delayed about 10 hours or so. There was a time … where they were supposed to be up on the surface. When that time passed, that is when the … worry and not so good feelings started.”

Christine Dawood said she had “loads of hope” during the international search for the Titan, noting that it was the “only thing that got us through it.”

“There were so many actions on the sub that people can do in order to surface,” she said of believing they may survive. “It was like a rollercoaster, more like a wave … We kept looking at the surface.”

Christine Dawood said she “lost hope” when they passed the 96 hour mark, sending a message to her family that she was preparing for the worst. Her 17-year-old daughter, Alina, was was still hopeful until the call with the U.S. Coast Guard about finding debris from the Titan.

Before the launch, she recalled how she was laughing and joking with her husband and son. She was “very happy for them” because her husband and son had wanted to go down to the Titanic for a long time. An earlier trip in which she would have joined was cancelled due to the pandemic. Suleman was too young at the time go on the voyage.

“Shahzada was so excited to go down. He was like a little child,” Dawood said. “They both were so excited.”

Her son, Suleman Dawood, had an unusual goal in addition to seeing the Titanic wreckage. “He said, ‘I’m going to solve the Rubik’s Cube at 3,700 meters below sea at the Titanic’,” she said, noting that they were planning to film it. “He was so excited about this.”

The U.S. Coast Guard announced Thursday that debris from the submersible had been found roughly 1,600 feet (488 meters) from the Titanic shipwreck on the ocean floor. The Titan imploded on its way to tour the Titanic wreckage, killing all five on board. Debris was located about 12,500 feet (3,810 meters) underwater.

Investigators from the U.S. Coast Guard, the U.S. National Transportation Safety Board, the Transportation Safety Board of Canada, the French marine casualties investigation board and the United Kingdom Marine Accident Investigation Branch are working closely together on the probe of the June 18 event that drew worldwide attention.

As the investigation intensifies, memorials and funeral services for the five people who died are expected to happen soon. Along with Shahzada Dawood and Suleman Dawood, those killed on the vessel were OceanGate CEO Stockton Rush, who piloted the Titan; British adventurer Hamish Harding; and Titanic expert Paul-Henri Nargeolet.

A funeral prayer service was held early Monday in Karachi, Pakistan for Shahzada Dawood and Suleman Dawood. Prayers will also be held for them Tuesday in Karachi at the Dawood Foundation, the charitable organization at which Shahzada was a member of the Board of Trustees.

“In loving memory of our beloved sons, please join the Dawood family as we pray to thank Allah for His immense blessings and forgiveness for Shahzada Dawood and Suleman Dawood,” the foundation said on Twitter.