Grant Seaver’s family gathers around a fire “cauldron” in City Park for a moment of reflection and comfort during Grant Seaver’s memorial service Saturday, Sept. 17, 2016. The 13-year-old passed away earlier in the week. (Tanzi Propst/Park Record)

The parents of one of the 13-year-old Park City teens who died of overdoses in 2016 are suing the companies they claim shipped, marketed, distributed and sold the drugs that led to the fatalities.

James and Deborah Seaver, the parents of Grant Seaver, filed the lawsuit on Friday in Utah’s U.S. District Court against the estate of the deceased Alexandre Cazes, who founded the now-defunct online dark web market AlphaBay; The Tor Project, Inc., a software that enables access to the dark web; and the postal services China Postal Express & Logistics Company and Express Mail Service. The Seavers claim in the lawsuit that the defendants are liable for the death of their son.

The lawsuit alleges that two Park City teens who purchased the synthetic opioid U-47700 that killed Grant Seaver did so through AlphaBay and The Tor Project’s software using cryptocurrencies. The suit claims China Postal Express & Logistics and Express Mail Service were aware that Chinese online sellers were using their services to ship illicit drugs to Americans.

Seaver’s parents in the lawsuit accuse the defendants of negligence, abnormally dangerous activity and civil conspiracy. At the time of the boys’ deaths, U-47700 was not listed as a Schedule I substance by the U.S. Drug Enforcement Administration, but the defendants knew the drug was more potent than morphine and “so unreasonably dangerous that ingestion of almost any amount could cause death,” according to the lawsuit.

The Seavers are seeking damages of more than $10 million, including for emotional distress and medical, funeral and cremation expenses.

In September of 2016, Grant Seaver and his friend, Ryan Ainsworth, died within days of each other after ingesting U-47700, commonly called pink. The tragedy sent shock waves through the Park City community that have continued to linger in the two years since.

In March, the Seavers also sued the parents of Ainsworth, the parents of a teen boy who pleaded guilty last year to purchasing the U-47700 and the parents of a 17-year-old girl prosecutors say was also involved in procuring the drug. The Seavers in the lawsuit claim the parents were aware or should have been aware of their children’s behavior but failed to inform law enforcement or others who could have acted to prevent Grant Seaver’s death.

The Seavers’ attorneys did not immediately respond to a request for comment.