Authorities say the former Forest Service worker who admitted starting Colorado's largest wildfire surrendered Monday to begin serving a six-year federal prison sentence.

Officials say 39-year-old Terry Lynn Barton was sentenced February 21st on federal arson charges. She turned herself into the Federal Medical Center in Carswell, Texas. Medical centers take prisoners with serious medical or mental health problems.

Meanwhile -- federal prosecutors filed a motion in the 10th US Circuit Court of Appeals to preserve the right to appeal a judge's denial of assigning restitution in the case. The federal government had requested $14.7 million dollars to cover firefighting costs and restoration of the Pike National Forest.

Barton also has been sentenced to serve 12 years on a single state arson charge but her public defender has appealed the state sentence because the judge may have been personally affected by the fire.