Niall Coti-Sears had developed many interests in his 23 years. He liked to play soccer, swim and ride horses with his grandfather. But mostly he loved music and the Marines.

He played guitar and classical piano, an instrument he excelled at, family members said.

“He never had to look at the music,” his grandfather William Coti said. “He would take a piece of Bach or Chopin or Mozart and he’d change it. He’d say, ‘I like this better.’ ”

Lance Cpl. Coti-Sears was killed last week in Helmand province, Afghanistan, while conducting combat operations, according to the Department of Defense. The Arlington County man was 23.

He was supposed to come home in October, his grandparents said.

Lance Cpl. Niall Coti-Sears was killed last week in Afghanistan, the Defense Department said. (Courtesy of Freedom Remembered)

“We’re proud and we’re devastated and we’re so angry,” his grandmother Mary Coti said.

“He was our beloved grandson,” Mary Coti said. “We practically raised him along with his mother.”

William Coti, a retired Marine colonel who served in Korea and Vietnam, said he used to tell his grandson stories about his experiences in those countries and once took him to a Vietnam veterans reunion.

“It was obvious he felt proud to be part of the Corps and had great respect for the veterans of Vietnam,” he said.

William Coti, 81, said that his grandson’s patrol was ambushed and that Coti-Sears died of wounds received in the attack.

Mary Coti, 80, said her grandson had always been good-hearted. After repeatedly rebuffing her attempts to get him to cut his unruly hair, Coti-Sears sent his hair to Locks of Love, the nonprofit that provides hairpieces to children suffering from long-term medical hair loss.

“He was a good boy,” Mary Coti said.

The Cotis said they will hold a memorial service for their grandson, although plans have not been finalized.