From a home base in Houston, federal authorities say, a Remington native has been directing a cross-country drug operation that shipped large quantities of heroin to Baltimore, New York, New Orleans and elsewhere.

Fred Douglas Brooks III, 46, had already served two federal prison terms for drug trafficking when he allegedly launched a new venture despite having betrayed a crew of Mexican suppliers by testifying against them in 2005. The latest business — a "high-level, interstate narcotics-trafficking and money-laundering operation," according to federal prosecutors in Louisiana — flourished until his arrest June 30 in Houston, authorities say.

At least 16 people, including Brooks, have been charged in connection with the case; seven are charged in U.S. District Court in Maryland.

Authorities say Brooks admitted to the scheme after being taken into custody. He is in federal detention, though it is not clear where. An attorney is not listed in court records.

His previous attorney, David B. Irwin, said he was "heartbroken" to hear Brooks was in trouble again. "He has very good qualities — I like him as a person," Irwin said.

Brooks is accused of bringing in multiple-kilogram shipments of heroin at a time into Baltimore, which a former federal prosecutor said would make him a relatively big player in the city's drug trade.

The amount of drugs alleged to be on the move in Brooks' case is "a lot," said Peter Nothstein, a former assistant U.S. attorney who worked on similar cases. He said heroin tends to come from West Africa or Southeast Asia and is therefore difficult to ship. "In time a new supply may get established, but it's not easy to do," Nothstein said.

Heroin in the Baltimore region carries an average wholesale price of about $60,000 per kilogram. Retailers cut down the purity two to four times, which results in thousands of doses that get sold for $5 each to street-level dealers, who charge customers $10 to $15.

A spokesman for the federal Drug Enforcement Administration said the agency could not comment on the charges Brooks is facing. The U.S. attorney's office also declined to comment.

Brooks was previously charged by federal prosecutors in 2003 — a complaint filed against him and his brother allege they were trafficking heroin between California, New York, Trinidad and Tobago, and Maryland. He was not sentenced until 2006, after he helped authorities by testifying against co-conspirators.

In that case, according to a news release from 2005, authorities alleged that drug dealers were moving hundreds of kilograms of cocaine into Baltimore from Los Angeles, with proceeds funneled back to Tijuana.

"He testified against other people as part of his cooperation agreement with the government," Irwin, his then-attorney, said this week. Brooks received 10 years in federal prison. Years later, his plea agreement remains sealed.

Despite Brooks' cooperation against his previous Mexican suppliers, authorities say he was able to re-establish cartel connections for his new operation.

Nothstein said cartels often function as a "giant logistics company, with the means to move contraband in a way most profitable." He said they are more involved in cocaine, but if there's a profit to be made from heroin, "they're willing to do it."

The DEA began another investigation into Brooks, in New Orleans, as far back as June 2012, while Baltimore police and federal agents began looking last year at a local drug dealing channel that they traced to Brooks.

Wiretaps on Brooks' phone showed he was in contact with people throughout the country coordinating drug shipments, according to a criminal complaint written by Special Agent Michelle Zamudio and filed against one of Brooks' alleged co-conspirators.

In New Orleans, authorities say, Brooks was directing the distribution of large shipments to two high-level area wholesalers, calling his product "love" and sending heart-shaped "emoticons" in text messages to indicate the number of kilograms to be sent.

In Maryland, investigators believe heroin shipments were picked up in Chicago through cartel connections, while drop-offs and payments were arranged in areas of suburban Baltimore like Pikesville and Edgewood, in Harford County. The drugs were ultimately funneled to the streets of Baltimore to be sold, officers wrote in court papers.

Among those charged with being part of Brooks' local pipeline is Sean Wilson, a 45-year-old from Pikesville who was involved in the majority of Brooks' recorded calls laid out in court records, and Timothy McDermott, an old partner of Brooks' who was indicted with him in the 1990s.

Citing GPS and phone tracking, agents wrote in court documents that McDermott traveled to Chicago in March, picking up three kilograms of heroin from associates of a Mexican source, making drops in Youngstown, Ohio, and West Virginia along the way.