Attorney General Jeff Sessions speaking in Indianapolis this week. (AP Photo/Darron Cummings) (Darron Cummings/AP)

In an effort to stem the increasing opioid-related overdose deaths, the Justice Department announced Thursday that anyone who possesses, imports, distributes or manufactures any fetanyl-related substance can be criminally prosecuted.

Justice officials said that overseas chemical manufacturers, aided by domestic distributors, try to evade regulatory controls by using analogues — or structural variants — of fentanyl that are not directly listed under the controlled-substance law. That has forced prosecutors to overcome difficult evidentiary hurdles to convict traffickers under another law, Justice officials said.

Attorney General Jeff Sessions said that the department’s action to include all fetanyl-related substances on the Drug Enforcement Administration “drug schedules” will give his prosecutors an important tool amid the nation’s opioid overdose epidemic.

“By scheduling all fentanyls, we empower our law enforcement officers and prosecutors to take swift and necessary action against those spreading these deadly poisons,” Sessions said.

Fentanyl is a powerful synthetic opioid, sometimes mixed into heroin or cocaine. Most illicit fentanyls come into the United States through the mail or express shipping systems or are imported across the southwest border, according to the Justice Department.

Every day, 55 Americans die from overdoses of synthetic opioids, according to the Centers for Disease Control and Prevention. The overdose death rate from synthetic opioids approximately doubled between 2015 and 2016 when more than 20,000 people died of overdose deaths, a Justice official said.

Last summer, the DEA warned police officers, firefighters and other first responders who might come into contact with fentanyl to be careful about touching or inhaling any powdery white substance. In a case in Ohio, an officer passed out about an hour after brushing the substance off his shirt. He was revived with four doses of naloxone, which blocks the effects of opioids.

In October, federal prosecutors charged two Chinese nationals who sold fentanyl to Americans over the Internet in a large international conspiracy case.

When Deputy Attorney General Rod J. Rosenstein announced the charges, he said that one of the men charged, Xiaobing Yan, operated websites that sold fentanyl to U.S. customers and also ran at least two chemical plants in China that could produce tons of fentanyl and fentanyl analogues. Rosenstein said then that fentanyl’s chemical structure can be modified to create analogues inside the bounds of U.S. and Chinese law.

Thursday’s action is aimed at targeting those modifications. A Justice official described the effort as way to stop the dangerous “Whac-A-Mole” game being played when manufacturers and distributors tweak the chemical structure of fentanyl to evade the law.

“DEA is seeing new fentanyl-related substances crop up at alarming rates,” said a DEA official. “This ... action gets us ahead of the chemists, ahead of the dealers, who would engage in this mad chemistry to avoid controlled substances.”

The Justice Department’s action on fentanyl variants is a temporary change to the DEA’s drug schedule and will last up to two years, with a possible one-year extension.

“I also urge the many members of Congress who clearly share our concern and alarm over fentanyl’s role in our opioid overdose epidemic to do their part by permanently scheduling these lethal substances,” Sessions said.