The operators of three shops in Adams Morgan and two gas station convenience stores in Anacostia have received written notice that they risk having business assets seized and forfeited under federal law if they sell fake pot, commonly marketed as K2 or Spice.

Narcotics investigators for the Metropolitan Police on Monday began visiting stores where they said they had previously made undercover buys or learned of sales of synthetic marijuana, said Inspector Brian Bray, commander of narcotics and special investigations.

Another three convenience stores are set to receive visits, Bray said.

The product is not illegal under District law or under state law in Maryland, although there have been proposals to outlaw it in both places. Virginia recently banned synthetic marijuana.

Spice cannot be detected by current urine testing methods and has become popular among military members, parolees and probationers who face random drug checks, said Bray. Eleven midshipmen have been expelled since January from the U.S. Naval Academy for using or possessing Spice in what is described as an ongoing investigation.

On March 1, the Drug Enforcement Administration banned five chemicals that are used to treat herbs to make them mimic the effects of marijuana.

The DEA is empowered to put a substance temporarily in Schedule I to avoid “an imminent threat to public safety” and acted, its spokesmen said, after increasing reports from emergency room doctors of convulsions, elevated heart rates and anxiety attacks among other side effects.

At the time of the DEA ban, 16 states had outlawed the herbal mix, which often is packaged in foil envelopes and labeled as incense.

Bray said it is selling in the District for about $40 a gram.

Users in the District could be prosecuted due to the DEA’s action, but it likely would be a minor drug case for federal court, said Bray, which is why investigators are focusing on putting stores on formal notice they stand to forfeit business assets for selling and distributing products containing the banned chemicals.

In addition to Spice and K2, the fake pot is sold as Wicked X, Bliss, Black Mamba, Bombay Blue, Fake Weed, Genie, Blaze, Dream, Ex-Ses, Spark, Fusion, Dark Knight, Yucatan Fire, Sonic, AK-47, Atomic Orange and Zohai.