22-year-old Michelle Kay Cole is suspected of buying vodka for 18-year-old Sylvia Garay.
Garay was driving an SUV near the McKinley exit off Highway 99 when she swerved. Her car flipped and a Greyhound bus crashed into her -- killing six people and injuring 22 others.
Investigators determined Garay had a blood-alcohol content of at least 0.11 at the time of the accident.
The district attorney has filed a misdemeanor charge of furnishing alcohol to a minor leading to a bodily injury against Cole. A warrant is out for her arrest.
