BOISE -- A Boise woman pleaded guilty Tuesday to fatally suffocating a man and dumping his body in the Boise Foothills.

Francis March, 45, admitted to first-degree murder as part of a plea deal that dropped additional charges of destruction of evidence and failure to notify of a death.

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March was arrested after the body of 61-year-old Mark Irwin was discovered inside a van the foothills in August 2016.

Prosecutors say March drugged Irwin and used a plastic bag to suffocate him before hogtying him to a plastic playground slide, wrapping him in a plastic tarp. She then stole the victim's vehicle to drive his body up to the foothills to dispose of it.

MORE: Boise woman denies murdering man found dead in foothills

March was arrested after she and 19-year-old Anthony Barclay tried to pawn a rifle that had belonged to the dead man. Barclay - who prosecutors say did not have a hand in killing Irwin - ultimately pleaded guilty to destruction of evidence and failure to notify of a death.

March has been held in the Ada County Jail on a $1 million bond since her arrest. She faces up to life in prison at her March 9 sentencing.