His family held a memorial on May 27 at a church in Bray, about 25 miles south of Dublin, Irish news outlets reported. The priest told mourners that Mr. Lawless texted his wife to say he had reached the summit and was headed home.

He was said to be an experienced climber who had reached the summit before. His expedition leader told The Times of London that Mr. Lawless was the victim of a “freak accident” after he unclipped himself from his safety ropes.

Ravi Thakar, 28

Mr. Thakar, an Indian climber, died on May 17 while in his sleep in his tent on the mountain’s highest camp site. Thaneswar Gurgai of Seven Summit Treks told The Associated Press that Mr. Thakar successfully reached the summit but began experiencing issues during his descent. Mr. Thakar’s body was discovered hours later.

Donald Cash, 54

Mr. Cash, of Utah, had achieved his goal of climbing the highest mountain on each of the seven continents, collectively known as the seven summits, before he collapsed on May 22. Mount Everest was the last mountain on his agenda. Mr. Cash, a former software salesman, quit his job in December to take on the final two mountains in his goal. After scaling Everest, he initially fainted at the summit, according to Pioneer Adventures, a company that organizes trips on the mountain. He collapsed again while descending near Hillary Step and could not be revived.

Image In this photo provided by Donald Cash’s family, he is seen training in the Wasatch mountains.

Anjali Kulkarni, 54

Ms. Kulkarni , of India, scaled the peak with her husband, Sharad Kulkarni. An expedition organizer told The Times of India that Ms. Kulkarni died from “energy loss” on her way back to Camp 4. A family friend, Ameet Singh, told the paper that the couple had climbed other mountains together, including Kilimanjaro.

“Their fitness level was good,” Mr. Singh said. “Besides, there was no bad weather, no contention on availability of Sherpas. This is a sad turn of events.”