BANGOR, Maine — The man who more than four years ago tipped law enforcement officials to a large marijuana farm in Township 37 was part of a similar operation in 2005 and 2006 allegedly run by the same people, according to a trial brief filed Tuesday by the prosecution in U.S. District Court.

Winston McTague, 48, of Newport will testify in the trial of three men accused of running the sophisticated growing operation that employed undocumented Hispanic workers, the brief, filed by Assistant U.S. Attorney Joel Casey, who is prosecuting the case, said.

McTague was not named in court documents filed earlier in the case.

When the Maine State Police flew a plane over the site on Sept. 22, 2009, people on the ground set fire to several buildings being used as dormitories before the suspected growers fled, according to a previously published report. The Maine Drug Enforcement Agency seized 2,943 mature marijuana plants from the farm.

Malcolm French, 52, of Enfield, Kendall Chase, 57, of Bradford and Rodney Russell, 50, of South Thomaston are facing a variety of charges in connection with the alleged operation on land owned by French. Their jury trial is scheduled to begin Wednesday in federal court in Bangor.

A fourth man, Robert “Bobby” Berg, 50, is set to plead guilty Tuesday to being an accessory after the fact to manufacturing 1,000 or more marijuana plants. In exchange for his guilty plea, federal prosecutors will drop three counts of harboring illegal aliens.

Berg is not on the prosecution’s witness list filed Tuesday.

Moises Soto, 53, of Nuevo Leon, Mexico, pleaded guilty last summer to a drug conspiracy charge and one count of harboring illegal aliens. He is expected to testify about his role in recruiting undocumented workers and his role as an overseer of the day-to-day operation of the farm.

McTague will testify that he met Chase years ago at a motorcycle event, then began growing marijuana with him in Danforth on property Chase said was owned by French, the brief said. Through these activities, McTague met French.

In 2005, McTague worked with Chase, French and others harvesting and processing marijuana growing on property French owned in LaGrange, according to the brief. McTague is expected to testify that the following year he worked on the LaGrange property and on land in Township 37 growing marijuana. He also helped Chase distribute the harvested marijuana.

“He will testify that Chase was the ‘brains’ of the operation because he knew how to grow marijuana,” the brief said. “McTague will testify that French financially backed the operation and provided land for the marijuana to be grown.”

McTague stopped working with Chase and French in 2007 after he suffered a shoulder injury and was seriously hurt in a motorcycle accident, according to the court document. He is expected to testify that he was not being paid by either defendant but had been promised he would make a lot of money.

“In 2008, [McTague] observed Kendall’s brother driving a load of peat moss through town and he followed,” the brief said. “He followed the load to Township 37. He parked his car and walked into the woods to see where the soil was going. He observed workers setting up a very large marijuana grow that was at a different location than the one he had worked at in Township 37

“He observed, Chase, his brother, French and some ‘Mexican’ workers setting up a growing operation in a large swamp,” the document said. “This was in 2008. Later in the year, McTague sent his first tip to the state police website. Investigators would not discover the grow until the following year [after McTague emailed officials again].”

When the marijuana operation was discovered in September 2009, Maine Drug Enforcement Agency officials characterized the size, scope and detail of the operation as quite surprising. They said the plants — many of them 8 feet tall and highly cultivated — were of extremely high quality.

“We have never seen this type of operation in Maine before,” MDEA Director Roy McKinney said in 2009. He confirmed that it was a plantation or farm, where caretakers of the crop lived 24 hours a day, seven days a week.

It took more than 60 state and federal law enforcement officers almost a week in the fall of 2009 to harvest the high-quality marijuana plants worth an estimated $9 million from a remote area, near the town of Wesley and about 10 miles off Route 9.

French and Russell are charged with: conspiracy to manufacture 1,000 or more marijuana plants, manufacturing 1,000 or more marijuana plants, maintaining a drug-involved place, harboring illegal aliens and conspiracy to distribute and possess with the intent to distribute marijuana.

Kendall was indicted on charges of conspiracy to manufacture 1,000 or more marijuana plants, manufacturing 1,000 or more marijuana plants, and conspiracy to distribute and possess with intent to distribute marijuana.

All remain free on bail.

Haynes Timberland Inc., the corporation that owns the land where the marijuana plot was discovered by law enforcement in September 2009, also was indicted.

Briefs filed by defense attorneys Walter McKee of Augusta, who represents French, William Maddox of Rockland, who represents Russell, and Jeffrey Silverstein of Bangor, who represents Chase, did not outline defense strategies. None of the defendants said they intend to take the stand.

The trial is expected to take two to three weeks.