Caplan said there were “obvious signs of trauma,” but Roswell police have remained tight-lipped about what occurred at the swimming pool.
According to the Fulton County Medical Examiner’s Office, Chico-Sims’ death was ruled a homicide by drowning that resulted from “a physical interaction with another individual.”
Johns Creek police told Channel 2 Action News that Chico-Sims, a Centennial High School student, sneaked out of her home, which was only a half-mile from where her body was discovered.
"The mother said she has snuck out of the house on occasion, typical teenage stuff," Johns Creek Lt. Todd Hood said Thursday. "Normally, in the morning, the family would find her. She'd be back home from whatever she was doing. Yesterday morning, she was not located at the house."
A maintenance worker found the teen’s body near the swimming pool of the Atlantic Newtown apartments on Nesbit Ferry Road apartment complex, police said.
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Channel 2 reported that Chico-Sims messaged a friend about meeting up around midnight Wednesday, but the friend told police she never showed up.
"We do show there is some activity on her Snapchat account at a certain time and after that, there hasn't been any additional activity," Hood said.
In a statement, Chico-Sims' parents said they were devastated to learn of their daughter's death.
"Beyond our grief, our commitment is to honor and remember the life of Mercedes with the support of our family and friends," the statement read. "If anyone has any information that will help in the investigation into Mercedes' death, please notify the police immediately ... Please remember Mercedes as you keep our family in your thoughts and prayers. We miss you Mercedes."
Fulton County Schools also released a statement.
“We are saddened to learn of this tragedy, and as the community mourns, we ask for respect for her family,” a district official said. “We are keeping them in our thoughts.”
Fulton County jail records show Foster was arrested two other times this year, once in late January on charges of first-degree burglary and theft by receiving stolen property, and again last week on a felony theft by deception charge.