PORTLAND – Conflicting reports about a Maine reservist’s death in Iraq have prompted the Army to launch an internal investigation that could take months to complete, a spokeswoman for U.S. Sen. Olympia Snowe said Monday.

The secondary inquiry was announced on the eve of Tuesday’s memorial service in Pennsylvania for Army 1st Sgt. Christopher Coffin, 51, of Kennebunk, who was assisting in rebuilding efforts when he died outside Baghdad.

The circumstances of his death have been shrouded in confusion.

The Army initially told Coffin’s wife, Betsy, that his vehicle ran into a ditch last week. But the Army also reported that a member of Coffin’s unit, the 352nd Civil Affairs Command, died when a convoy was ambushed.

The Army’s initial investigation has left many questions unanswered, said Elizabeth Wenk, spokeswoman for Snowe, R-Maine.

Consequently, Army generals at U.S. Central Command in Doha, Qatar, will conduct an official board of inquiry, she said.

Acting Army Secretary Les Brownlee notified Coffin’s family of the investigation Sunday night. The investigation could require 90 to 120 days or a shorter period of time, Wenk said.

Family members had been hoping to get a full accounting of Coffin’s death before the memorial service in Bethlehem, Pa.

“We want the truth, and that’s all we’re asking for,” Candy Barr Heimbach, Coffin’s sister-in-law, said Monday. “It’s a horribly painful thing for my sister not to have the answers now.”