The Coast Guard has new information about the mysterious deaths of two of its divers in the Arctic Ocean.
Four months ago, Jessica Hill and Steven Duque were part of a scientific expedition collecting data 500 miles north of Alaska. But something went wrong after the two plunged into the icy waters through a hole in the ice for a training mission.
Autopsy reports reveal the two were 20 feet below the ice when they suddenly descended to nearly 200 feet in a matter of minutes. It would normally take 30 minutes to reach that depth.
"Whatever happened beneath the ice marks the first Coast Guard diving deaths in 30 years," Jessica Hill's father, Jim Hill, told ABC News.
Relatives say a crewman on the surface told them Duque descended so forcefully they couldn't hold his safety line to keep him from dropping. When the two were finally pulled up, their tanks were nearly empty.
Despite efforts to revive them, they both died.
After the tragic dive, the families were told by investigators that something pulled the two divers down -- but what it was exactly could not be explained.
After the incident, Duque's family, including his sister, went to Seattle and visited the ship's crew to look for answers.
"We're very anxious to find out more info. We're anxious for the Coast Guard to give us more of an idea, a clue," Nathalie Duque Bello said.
"Nobody understands what happened or what went wrong," Hill said.
The sense of confusion contrasts with the scene a year ago when the Coast Guard divers were on top of the world -- literally.
An ABC News crew met Duque and Hill following a dive beneath the polar ice in the Arctic. Hill described the experience this way: "Visibility is incredible. The ice really looks like clouds underneath."
Now her death remains a mystery that's left two families shattered.