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LONGMONT, Colo. — A two-year-old Longmont girl is back home after spending New Year’s Eve in the hospital. She tested positive for THC, the primary psychoactive ingredient in marijuana.

The incident, which remains under investigation, happened on Tuesday when a mother told police she stumbled upon her daughter eating a cookie left sitting in the front yard of an apartment complex.

An hour after eating the cookie, the toddler’s mom rushed her to a Longmont hospital when she realized her daughter was acting strangely.

“She was sleepy, she was opening and closing her eyes, and she couldn’t walk very well,” said Aida Hernandez in an interview with FOX31 Denver Thursday.

The toddler returned from the hospital Wednesday but police are still trying to figure out where the possibly toxic cookie came from.

A Longmont police spokesperson confirmed the Hernandez family is cooperating in the investigation and says investigators believe the THC did not come from within the family’s apartment.