The Sicily-Rome American Cemetery and Memorial in Italy. GETTY IMAGES/ISTOCKPHOTO

2nd Lt. Allan W. Knepper took off from Tunisia in his P-38 "Lightning" aircraft as "one of many fighter waves" set to attack enemy Axis forces in Sicily, Italy on July 10, 1943.

During the attack, air forces were dispatched every 30 minutes, dodging enemy fire as they strafed an armored German column.

Knepper, 27, and the 49th Fighter Squadron encountered heavy anti-aircraft fire. Another pilot reported witnessing his plane "veer suddenly skyward before rolling halfway over and plummeting to the ground." No evidence was found that he deployed his parachute, and Knepper was declared missing in action, his remains never found.

Now, more than 80 years later, the Defense POW/MIA Accounting Agency has announced that they have accounted for Knepper's remains, bringing peace to his last surviving family member.

The DPAA did not specify how they accounted for Knepper, or what remains of his were used to make the identification. Since the 1970s, the agency has accounted for the remains of nearly 1,000 Americans who died during World War II. The remains are returned to families for burial with full military honors, the agency said.

Knepper was memorialized on the Tablets of the Missing at Sicily-Rome American Cemetery in Italy, according to HonorStates.org, a site tracking military members. The military typically marks such names with a rosette or other symbol once their remains have been accounted for, but the DPAA did not say if this would be done for Knepper.

Knepper posthumously received a Purple Heart and an Air Medal, the site said.

Knepper's life has also been memorialized in "The Jagged Edge of Duty: A Fighter Pilot's World War II." The book, written by historian Robert Richardson, tracks Knepper's life and death and even offered some insight about where his remains might be found. It also offered closure to Knepper's only surviving relative, 79-year-old Shirley Finn.

"I felt like I finally met my brother," said Finn in an interview with the Lewiston Tribune. Finn is Knepper's half-sister, the paper said. Finn said that her family "never lost hope" that Knepper's remains would be found.

"I am tremendously grateful for (Richardson)," she told the Lewiston Tribune in 2017. "I didn't think anyone would be interested in reading a book about my brother. I didn't think other people would care. It just didn't occur to me."