BOISE -- A Meridian woman accused of huffing compressed gas just before a fatal collision in September has pleaded not guilty.

Shelly Wilson, 52, entered the not-guilty plea to felony vehicular manslaughter Monday. She has been held in the Ada County Jail on a $500,000 bond since her arrest.

MORE: Prosecutor: Driver was huffing gas before deadly Fairview collision

Prosecutors say Wilson was impaired from inhaling the compressed gas when she caused the chain-reaction crash on Fairview Avenue east of Eagle Road. According to police, Wilson did not hit her brakes before rear-ending a 2016 Buick driven by 73-year-old Patricia Ann Shannon of Meridian.

The impact caused Shannon's car to hit two other vehicles. She was pronounced dead at a local hospital.

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Prosecutors say Wilson failed a horizontal gaze test officers use to determine drug impairment immediately after the crash, and does not have any memory of the collision.

Trial in the case has been set for May 2018. If convicted, Wilson could face up to 15 years in prison.