An Army reservist whose retirement request was denied because of Operation Iraqi Freedom became the fifth soldier with Maine ties to be killed in the conflict, possibly when his convoy came under attack.

First Sgt. Christopher Coffin, 51, of Kennebunk was a member of the 352nd Civil Affairs Command assisting convoys traveling between Baghdad and Kuwait when he died Tuesday, his sister-in-law, Candy Barr Heimbach, said Wednesday.

The Army initially told the family Tuesday night that Coffin was driving a vehicle that crashed after swerving to avoid an Iraqi civilian vehicle.

But the family asked for an investigation into the incident after news reports based on an Army statement indicated a member of the same unit died after a rocket-propelled grenade hit a truck during an ambush outside of Baghdad.

U.S. Sen. Susan Collins, R-Maine, said Wednesday she received assurances from the Army that there will be a full investigation.

Coffin, who moved to Maine with his wife Betsy 15 years ago, had planned to retire, but his plans changed when war came, Heimbach said.

“He made a commitment to my sister to spend their older years together and not to put himself in jeopardy, where there’d be any chance she’d have to suffer through what she’s going through now,” she said.

Coffin’s body was being flown to Bethlehem, Pa., where a funeral likely will be held on Tuesday, which would have been his birthday, at the Trinity Episcopal Church where the couple married, Heimbach said.

U.S. Rep. Tom Allen, D-Maine, joined Collins and Gov. John Baldacci in expressing condolences to Coffin’s family.

“Sergeant Coffin’s death is a grim reminder to us that much work remains to be done in Iraq to restore civil order, rebuild the economy and create an institutional framework for the Iraqi people to govern themselves,” Allen said.

Coffin, who was deployed overseas four months ago, was part of a unit based in Riverdale, Md., that was assisting with rebuilding efforts and was not supposed to be involved in active combat.

Heimbach described her brother-in-law as devoted to his wife, family, friends and country.

“He was a man committed to the ideals and values of this country. He took pride in being a soldier,” she said. “If anyone exemplified the values and the understanding of the need to defend our values, it was Chris.”

Heimbach said Coffin, who worked at Portsmouth Naval Shipyard, will be missed by his wife and family members, including her 16-year-old twin boys who idolized their uncle and hoped he would teach them to drive. Betsy and Christopher Coffin had no children of their own.