Katadzic has not dived the final kilometer to where the boys are stranded on a muddy bank, the most unsafe part of the dive, during which rescuers have to hold their oxygen tanks in front of them to squeeze through submerged holes.
"Once his mission was over he dove back, but in the middle of their return his buddy found Samarn unconscious in the water and tried to pump his heart, but he could not save his life", the SEAL unit said in a statement.
The boys are now learning how to swim and scuba dive because some parts of the cave are too narrow for more than one person to pass. Water levels continue to fall in the cave, but heavy rain is forecast for as soon as Friday afternoon, breaking a relatively dry spell in recent days.
A screengrab of a video, posted by the Thai Navy SEALs, of the stranded soccer team. Medical assessments indicated the trapped children have good oxygen levels, with all of them having oxygen saturation levels of 95 percent and above.
Rescue teams above ground have drilled more than 100 holes in a bid to find a route to the trapped Thai cave boys, Osottanakorn said, but "it doesn't look promising".More news: Scott Pruitt resigns as chief of United States Environmental Protection Agency
That plan was dropped after rescuers realized the 12 boys, ages 11 to 16, and their 25-year-old coach are too weak and too inexperienced to attempt the harrowing journey out of the cave. "I promise to take the very best care of the kids", he said in a note given to divers on Friday.
"Thank you for all the moral support and I apologise to the parents".
I'm OK, don't worry about me too much. But don't forget to do my birthday party. Some asked for fried chicken, while others simply told their parents that they loved them. "With love." The name reference could be of a waiting relative.
One boy, Mick, wrote: "Don't be anxious, I miss everyone". I miss you all, grandpa, uncle, mom, dad and my siblings. Monsoon flooding cut off their escape and prevented rescuers from finding them for nearly 10 days as the only way to reach them was by navigating dark and tight passageways filled with muddy water and strong currents.
Boys trapped in a Thai cave wrote letters to their parents on Friday, telling them to "be strong" and not to worry.
The official in immediate charge of the operation, Gov. Narongsak Osatanakorn, indicated strongly at a midnight news conference that if heavy rains started and appeared to be causing flooded areas in the cave to rise again, they would try to take the boys out with divers right away.More news: Russian Federation enjoying advantage at World Cup due to fan support
"I talk to them every day, if they'd like us to take the kids out, it has to be in the minimum risk", he said.
Rescue divers on Tuesday found twelve teenage soccer players and their coach alive after they went missing in a Thai cave more than ten days ago. He said the boys were still healthy and have practiced wearing diving masks and breathing in preparation for the diving possibility.
Around 1,000 people are involved in the complex rescue operation. The path out is considered especially complicated because of twists and turns in narrow flooded passages.
The latest was Elon Musk, the entrepreneur behind the Tesla automobile and the SpaceX rocket company, who said he would send engineers to help.More news: U.S. tariffs on China take effect as Trump trade war escalates