Their efforts included trips to the Pentagon and even meeting with President Bush, but they ended in disappointment Sunday: An Army general told them the remains of Maupin, a soldier who had been listed as missing-captured in Iraq since 2004, had been found.
"My heart sinks, but I know they can't hurt him anymore," Keith Maupin said after receiving word about the remains of his son, who went by Matt.
On Monday, Defense Secretary Robert Gates expressed sympathy to Maupin's family.
"This has been especially difficult for the Maupin family because of not knowing for almost exactly four years. So I want to extend my condolences," Gates said, speaking to reporters aboard a flight to Denmark.
The Army didn't say how or where in Iraq his son's remains were discovered, only that the identification was made with DNA testing, Maupin said. The discovery of a shirt worn by soldiers at the time Matt was captured helped the Army focus its search.
The Department of Defense issued a terse statement Monday announcing an official change in status from missing-captured to deceased. There were no details of how and when Maupin died or where his remains were found.
The Army was continuing its investigation, Maupin said.
Matt Maupin was a 20-year-old private first class when he was captured April 9, 2004, after his fuel convoy, part of the Bartonville, Ill.-based 724th Transportation Company, was ambushed west of Baghdad.
A week later, the Arab television network Al-Jazeera aired a videotape showing a stunned-looking Maupin wearing camouflage and a floppy desert hat, sitting on the floor surrounded by five masked men holding automatic rifles.
That June, Al-Jazeera aired another tape purporting to show a U.S. soldier being shot. But the dark and grainy tape showed only the back of the victim's head and not the execution.
The Maupins refused to believe their son was dead. They lobbied hard for the Army to continue listing him as missing-captured, fearing that another designation would undermine efforts to find him.
The Pentagon agreed to give the Maupins regular briefings, and Bush met with them when he traveled to Cincinnati.
Keith Maupin said the Army told him soon after his son's capture that there was only a 50 percent chance he would be found alive. He said he doesn't hold the Army responsible for his son's death, but that he did hold the Army responsible for bringing his son home.
"I told them when we'd go up to the Pentagon, whether he walks off a plane or is carried off, you're not going to leave him in Iraq like you did those guys in Vietnam," Maupin said.
Keith Maupin and his ex-wife, Carolyn, held a candlelight vigil Sunday night outside the Yellow Ribbon Support Center in Batavia, an office they used to package thousands of boxes of donated snacks and toiletries for shipment to soldiers in Iraq.
"It hurts," Carolyn Maupin said. "After you go through almost four years of hope, and this is what happens, it's like a letdown, so I'm trying to get through that right now."
On Monday, the Maupins rode as planned in the baseball season opening day parade for the Reds in downtown Cincinnati.
"It was important to be here to let everyone know that we thank them for their support and their love of our family and for standing by Matt as they are today," Carolyn Maupin said.
Despite a light rain, the Maupins rode in an open convertible and were greeted with applause and cheers all along the parade route. "That touched my heart," she said. "I don't think they'll forget him."
The Maupins were told by an Army official on Friday to expect an update on their son over the weekend, Keith Maupin said. The Army broke the news about their son's remains at a somber meeting.
"When you look out there in the parking lot and see a three-star general get out of a car, you know it ain't good news," Keith Maupin said.
Four U.S. service members remain missing in Iraq: Capt. Michael Speicher, a Navy pilot, has been missing since the 1991 Persian Gulf War; Sgt. Ahmed al-Taie, a 41-year-old Iraqi-born reserve soldier from Ann Arbor, Mich., was abducted while visiting his Iraqi wife in October 2006 in Baghdad, and Pfc. Byron Fouty and Sgt. Alex Jimenez have been missing since May 12.
Matt Maupin graduated from Glen Este High School, just east of Cincinnati, in 2001 and attended the University of Cincinnati for a year before joining the Army Reserves.
Dan Simmons, the athletic director at Glen Este, remembered him as a quiet but hardworking backup player on the school's football team.
"Matt was a selfless kid on the football field," Simmons said. "He did whatever the coaches told him. He wasn't a starter, but he made the other kids play harder."
A month after his capture, Maupin was promoted to the rank of specialist. In April 2005, he was promoted to sergeant.