Kevin Lamarque / Reuters

Lesleigh Coyer, 25, of Saginaw, Michigan, lies down in front of the grave of her brother, Ryan Coyer, who served with the U.S. Army in both Iraq and Afghanistan, at Arlington National Cemetery in Virginia on March 11, 2013. Coyer died one year ago.

At 26, Staff Sgt. Ryan Coyer already had a lifetime of accomplishments: four tours to Afghanistan, two tours to Iraq, and being named a member of the elite U.S. Army Rangers. 

On Monday, the eve of the one-year anniversary of Coyer’s death, his family gathered at his graveside to commemorate that lifetime of accomplishments, unexpectedly cut short when Coyer died of cardiac arrest.

"The kid could do anything he wanted as long as he put his mind to it," Anthony Coyer, Ryan’s father, told Michigan’s MLive.com last year of his son, who was born in Nashville but grew up in Saginaw, Mich., playing football and frequently landing on the honor roll. "He wouldn't admit that."

Coyer enlisted in the Army in 2004, according to his obituary, posted by Snow Funeral Home in Saginaw. He was 19 when he enlisted; his father said he had made the decision to leave Saginaw — a town of 52,000 — for boot camp in Georgia when he was still a high school senior.

"Before he graduated [high school], he signed himself up," Anthony Coyer told MLive.com. "He did it on his own and he came home one day and told his mom and dad what he was going to do."

Six months after enlisting, according to his obituary, Coyer was assigned to the 75th Ranger Regiment, the special operations command unit of the U.S. Army Rangers.

Soon Coyer was deployed overseas, then deployed again — and again. In between his two tours of duty in Iraq and four in Afghanistan, Coyer wouldn’t talk much about what his prestigious team did in combat.

"We just know that he ... served to protect and defend this country, and he did a damn good job of it," Anthony Coyer told MLive.com.

Coyer had been back on base at Hunter Army Airfield in Savannah, Ga., on March 12, 2012, when he suddenly died of cardiac arrest. Further details surrounding his death weren’t made public.

Efforts by NBC News to reach Coyer's family on Tuesday were unsuccessful. 

Lesleigh Coyer, his younger sister, called her only sibling a protective "best friend" who was never quick to like the guys she chose to date. She told MLive.com that she and her brother, just two years apart, used to get into mischief all the time, such as toilet papering their neighborhood late at night. 

The final resting place for Lesleigh Coyer’s partner-in-mischief — a decorated serviceman who loved lifting weights and riding his motorcycle, his obituary says — is Arlington National Cemetery. On Monday, a Reuters photographer took a picture of Lesleigh curled up on the ground in front of her brother’s grave, grieving. She and her parents were visiting the military cemetery in Virginia from Saginaw a day before the one-year anniversary of Coyer’s death.

 "I looked up to him," Lesleigh Coyer told MLive.com via text days after her brother’s death. "I leaned on him, just as he did me ... He was a great man and I was honored to be his sister."

NBC News’ David Arnott contributed to this report.

Kevin Lamarque / Reuters

Tony Coyer puts his hand on the shoulder of his daughter Lesleigh as his wife Mary weeps while visiting the grave of his son.

This story was originally published on Tue Mar 12, 2013 7:19 AM EDT