Two 13-year-old Park City boys who died unexpectedly at their homes in September overdosed on U-47700, a synthetic opioid commonly referred to as pink, the Utah State Medical Examiner’s Office has determined.

The Park City Police Department had suspected overdoses as the causes of the deaths of Ryan Ainsworth and Grant Seaver, students at Treasure Mountain Junior High School and best friends, but had been unable to confirm that until receiving toxicology reports from the medical examiner.

Police announced the results of the toxicology reports Thursday morning but declined to comment further, citing the ongoing investigations into the deaths.

The deaths of the boys shook the Park City community in September and set off wide-ranging discussions about the prevalence and dangers of drugs in the area’s schools. The medical examiner’s determinations confirmed what many parents and residents had feared — that the problem has turned deadly.

The police announcement came a day before a 15-year-old boy was scheduled to make his initial appearance in court on felony charges stemming from the investigations into the deaths. The teen, charged with one second-degree felony count of distributing a controlled substance and one Class A misdemeanor count of reckless endangerment, allegedly ordered U-47700 online from China with a friend.

According to a search warrant detailing the teen’s actions, he and the friend, also a teen boy, distributed the drug, which is twice as potent as heroin, to two other friends. It is unclear whether Seaver and Ainsworth received U-47700 from the teens.

Patricia Cassell, chief prosecutor with the Summit County Attorney’s Office, said there will be no additional charges against the 15-year-old boy in light of the toxicology reports from the medical examiner.