Nineteen year-old Andover resident Zachary Zimmerman pleaded not guilty on Thursday, Aug. 20 after being charged with providing alcohol to minors at a Feb. 14 gathering at his William Street home.

The case has received significant attention because a party-goer, Elizabeth Mun, a 16 year-old schoolmate from Wellseley, wandered from the Valentine's Day gathering and was later found face down in a pond. Zimmerman's mother, Laurie, was not home the night of the incident.

"The medical examiner's office ruled that the cause of death was drowning and that the manner was suicide," Essex Assistant District Attorney Jessica Connors told the court. "The ME further ruled that her consumption of alcohol was not a contributory factor to her death."

Zachary Zimmerman's case will be heard at a pre-trial conference on Sept. 29.

Another teen at the February gathering, Morgan Ingari, 18, of Winchester, was also charged with providing alcohol to minors. Ingari appeared in court on Aug. 20 with Zimmerman, and admitted to sufficient facts in the case. Her case was continued without a finding for two years and she was placed on probation. Ingari must complete 50 hours of community service.

As she heads off to college, Ingari is also forbidden from drinking alcohol and is subject to random screens. The district attorney's office says that Ingari used a fake ID to purchase beer and vodka for the party after being driven to a nearby liquor store, allegedly by Zimmerman.

Mun, a Concord Academy student, was reported as missing to the Andover police at 6:50 a.m. on Feb. 15. She had been last seen at the William Street gathering arounc 5 a.m., and made a cell phone call at 5:27a.m.

During the search, police used Mun's cell phone signal to track her. She was found unresponsive in Hussey Brook Pond at 10:46 a.m. and pronounced dead that afternoon in a Boston hospital.