A pair of search warrants unsealed Monday show how a pair of Park City teens may have purchased the synthetic opioid U-47700, shedding light on the police investigations of the deaths of two other teens last month.

The warrants were filed Sept. 13 by the Park City Police Department after 13-year-olds Grant Seaver and Ryan Ainsworth, best friends, were found dead in their homes. Police, who are awaiting toxicology reports from the state medical examiner to determine causes of death, are investigating whether the boys overdosed, potentially on U-47700.

According to the warrants, filed in 3rd District Court in Silver Summit and 4th District Court in Heber City, a juvenile girl reported to police that she had received a package through the mail in August that contained drugs for a pair of teen boys. The boys had told the girl they could not receive the shipment to their own homes because their parents screen their mail for drugs.

One of the boys told his therapist that the drug was U-47700, according to the warrants.

The girl told police that one of the boys had ordered the package, which contained white powder in a clear bag, over the dark web from China, the warrants state. The dark web is a section of the internet accessed through special software and commonly used to buy and sell drugs.

As a result of the warrant, police seized a number of computers and cell phones from two houses, one in Park City and another in Heber City.

After receiving the package, the girl gave the drugs to the teen boys, who distributed it to two underage friends, according to the warrants. Police recovered a cardboard package from the girl’s mother. The contents of the package are labeled as “Sample.”

In the aftermath of the deaths of Seaver and Ainsworth, police warned the community about U-47700, which is twice as potent as heroin. Officials said at the time that they had no clear evidence indicating the boys had died of overdoses, but they had been talking with their friends on social media about synthetic opioids.

The warrants do not, however, mention the deaths of Seaver or Ainsworth and don’t indicate whether they received any drugs from the boys who ordered the package from China.

Park City police did not immediately respond to a phone call seeking comment.

U-47700 is twice as potent as heroin, according to the DEA. U-47700 overdoses have been confirmed in two deaths in Utah, in Salt Lake and Iron counties. The DEA has invoked an emergency measure to classify the drug as a Schedule I substance, making it illegal to buy or possess. That measure was set to take effect Oct. 7.

The deaths of Seaver and Ainsworth, and the possibility that drugs were involved, have sparked wide-ranging discussion in Park City about the reality that drugs are in schools and on the streets.