COLORADO SPRINGS, COLO. ? A former U.S. Forest Service employee accused of starting a forest fire that devoured 137,000 acres and more than 130 homes last summer is expected to change her plea from innocent to guilty, a spokesman for prosecutors has confirmed.

Terry Barton, 38, pleaded innocent in late June to sparking the Hayman fire.

Barton was scheduled to go to trial Jan. 6 on four federal charges: setting fire to a national forest, damaging federal property, using fire to commit a felony and injuring a firefighter. The last charge arose when a firefighter broke an arm. If convicted of all charges, Barton faced a prison sentence of as long as 60 years and up to $1 million in fines.

Jeff Dorschner, spokesman for U.S. Atty. John Suthers, confirmed prosecutors reached a plea agreement with Barton. He said details of the plea would not be revealed until Dec. 6 when Barton appears before U.S. District Judge Richard Matsch for a change-of-plea hearing.

Investigators said Barton told them she accidentally started the fire while burning a letter from her estranged husband in a fire pit. Authorities, though, say forensic evidence gathered from the pit indicates the blaze was intentional.

The Hayman fire, which rushed through drought-dried forests, cost the federal government almost $33 million to fight. It is expected to cost as much as $150 million to rehabilitate a swath of burned forest running from Lake George to the outskirts of Denver.