A Carpentersville teen who drowned after driving into a Vernon Hills retention pond in December was intoxicated and had consumed cannabis prior to her death, the Lake County coroner’s office said.

Brissa Romero’s blood alcohol content registered at 0.16, twice the legal limit of 0.08, toxicology test results obtained by the coroner’s office showed. She also had THC, found in cannabis, in her system, results showed.

Neither caused her death but did contribute, Chief Deputy Coroner Stephen Newton said.

“The official cause of death for Ms. Romero is drowning in a retention pond with ethanol intoxication as a contributing factor, and it has been ruled an accident,” Newton said.

Romero was last seen Dec. 3 when she visited cousins living in Des Plaines and then drove to a holiday party being held at a Bowlero entertainment venue in Vernon Hills.

Her family reported the 2023 Barrington High School graduate missing to Carpentersville and Vernon Hills police when she didn’t return home and couldn’t be contacted the following day.

Police investigators ultimately found her 2008 Nissan Rogue in a retention basin at Executive Way and Lakeview Parkway in Vernon Hills on Dec. 11 and recovered her body from the water a day later.

Surveillance video taken about 15 minutes before her cellphone signal was lost showed she went into and exited a nearby fast-food restaurant, prompting police to check ponds in the area. A woman walking near the pond spotted a backpack later identified as belonging to Romero.

Police believe the teen accidentally drove through a T-intersection and into the 2-acre lake, which is about 20 feet deep.

Gloria Casas is a freelance reporter for The Courier-News.