A retired Army National Guard soldier from metro Atlanta died Saturday, 10 years after he was shot in the head while searching for Army Sgt. Bowe Bergdahl in Afghanistan.

Master Sgt. Mark Allen was injured in a June 2009 search mission for Bergdahl, who walked off a U.S. military outpost and was captured by the Taliban. Military prosecutors said Allen was shot during a firefight that erupted when U.S. forces and about 50 members of the Afghan National Army were attacked by enemy fighters.

RELATED: Bergdahl: Firefight recalled in search for missing soldier

Allen suffered a traumatic brain injury that left him in a wheelchair and unable to communicate. His wife, Shannon Allen, told WSB Radio that she did not learn about the circumstances surrounding her husband's injuries until 2014, after former President Barack Obama negotiated Bergdahl's release in a swap for five Taliban members detained at Guantanamo Bay.

MORE: Searchers' wounds will be considered at Bergdahl sentencing

Shannon Allen has declined interviews, but she was in the court room in October 2017 when Bergdahl pleaded guilty to charges of desertion and misbehavior before the enemy, The Associated Press reported. He was later sentenced to a dishonorable discharge from the Army but avoided prison time.

Shannon Allen again declined an interview Monday with WSB Radio.

Army Sergeant And Former Captive Bowe Bergdahl Pleads Guilty To Desertion

When Mark Allen returned home, after being treated for three years at a military hospital in Florida, he was honored as a hero. The father of two was a frequent recipient of local accolades in his Walton County hometown.

"I'm heartbroken to let you all know that my husband passed away peacefully yesterday morning, with his family by his side," Shannon Allen said Sunday in a post to her business Facebook page. "Over ten years ago, he sustained a severe head injury while serving In Afghanistan, which caused him lifelong health problems. These past few months, he has faced some significant illnesses, and his body was finally ready to rest."

According to an obituary printed in the Walton Tribune, Allen spent 21 years in the Army and the Army National Guard. He retired in 2013 upon receiving a Purple Heart. He is survived by his wife, his son, Cody, and a daughter, Journey.

Gov. Brian Kemp offered his condolences to the family.

“Master Sgt. Mark Allen was a member of  the Georgia National Guard⁩ 48th Infantry Brigade Combat Team,” Kemp said on Twitter. “He was a true American hero who will be missed by our entire country. Georgia First Lady (Marty Kemp), the girls, and I extend our⁩ thoughts and prayers to his loved ones.”

Services are planned for this week. Visitation will be from 4 to 8 p.m. Thursday at Tim Stewart Funeral Home in Loganville. A funeral is set for 11 a.m. Friday at the First Baptist Church of Snellville, with a burial to follow.

— The Associated Press contributed to this article.

Sgt. First Class Mark Allen was shot in the head while he searched for deserted soldier Bowe Bergdahl.