The heroin — 105 pounds of it — was hidden in foot lockers and tool chests inside a small Northeast Washington rowhouse. A press used to package drugs was in the kitchen. The guns were in the bedroom, one tucked under a pillow on the bed.

Authorities detailed these items in a federal court document outlining what they described as one of the D.C. region’s largest heroin busts.

The heroin — worth an estimated $4 million — was laced with fentanyl, according to authorities, who cite it as an example of how the powerful drug is distributed in large quantities. It also demonstrates the use of the deadly opioid additive that itself is 50 times more potent than heroin and blamed for mounting overdose deaths in the District and around the country.

“Because we have removed this heroin from our streets, we know that we have saved lives,” Mayor Muriel E. Bowser (D) said in announcing the arrests, noting the heroin was sold in neighborhoods along Minnesota and Alabama avenues.

Law enforcement agencies including D.C. police and the Bureau of Alcohol, Tobacco, Firearms and Explosives, announced arrests in the undercover case on Monday. New court filings offer additional details about an operation that authorities say involved a car repair shop in Maryland and a suspect who had a residence in Baltimore.

Documents in federal court in the District describe how a federal agent posing as a drug dealer twice in November exchanged more than $10,000 in cash for guns and heroin while sitting in a vehicle. One court document says one of the suspects warned the agent that the heroin is “completely pure, to the point that the fumes associated with the heroin would cause individuals to vomit.”

Police said they arrested Linwood Douglas Thorne, 46, who lived in the house on Foote Street in Northeast where police said the drugs were stored. Authorities did not identify the second suspect and said that case is under seal.

Thorne appeared in U.S. District Court on Thursday but chose not to contest his detention. His attorney, Danielle Jahn with the Federal Public Defender’s office, said his client’s family was planning to hire a private attorney who might ask for release pending trial at a later date. A federal magistrate judge continued Thorne’s detention.

Thorne appeared in court limping and using a cane; Jahn told the judge the defendant fell in the D.C. jail and required a brief hospital stay. Thorne patted his heart with his right hand as he briefly glanced at relatives who had come to support him.

Jahn did not contest arguments prosecutors made in court papers calling her client a danger and a flight risk. Outside court, Jahn declined to comment, noting she was serving as his attorney only temporarily.

Thorne was convicted of selling drugs in 1995 in Maryland after he and others purchased more than two pounds of crack cocaine from an undercover informant for Montgomery County police in the parking lot of a Bob’s Big Boy restaurant. Police said they found a .357 Magnum handgun in a vehicle Thorne had been using.

In that case from the 1990s, Thorne pleaded guilty in federal court to distributing cocaine and was sentenced to nearly 16 years in prison, though his penalty was reduced and he was freed from a federal prison in 2008 after sentencing reforms.

Assistant U.S. Attorney Gregory P. Rosen argued in court papers last week that Thorne should be committed until trial, writing that his 1994 case coupled with his most recent arrest “reflects multiple crimes in which the defendant was, again, acting as a wholesale supplier, trafficking significant amounts of illegal narcotics while possessing a firearm.”

The most recent investigation into Thorne began in July 2018, according to court documents, when an ATF agent posing as a drug and arms buyer purchased weapons and marijuana from the as yet unidentified arrestee. Court documents state the undercover officer then inquired about buying heroin.

Authorities said the first purchase occurred Nov. 1, 2018, when the agent paid $700 for guns and $10,800 for 131 grams — or 4.6 ounces — of heroin in an unspecified location. Police said the second sale was the afternoon of Nov. 29 in a grocery store parking lot on Alabama Avenue. Court documents say the officer paid the same suspect $10,300 for 129 grams of heroin.

Police said that during the course of their investigation, they traced phone calls between the two suspects to an auto repair shop off a dead-end road in Clinton. Police said they found 9mm ammunition during their search of the shop.

Inside the house on Foote Street in Northeast, police said they seized 105 pounds of heroin, 55 pounds of marijuana, the drug press and six handguns. Court documents said that in addition to Thorne, another adult and two children live at the residence. Thorne was arrested at a rowhouse in Baltimore’s Reservoir Hill neighborhood, a half-mile from the epicenter of the 2015 riots.

The second defendant was arrested in Fairfax County, Va.

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