Posted by Matt Rocheleau July 10, 2013 11:07 AM

Two Colombian nationals face charges of sex trafficking and running a prostitution house in Allston following a year-long, ongoing investigation that led to their arrest, authorities said.

Hector Gallego, 50, and Wider Gomez Agudelo, 41, were ordered by a judge to be held on $75,000 bail and held on immigration detainers at their arraignments last week in Brighton District Court, according to Suffolk County District Attorney office spokeswoman Renee Nadeau Algarin.

Both men pleaded not guilty to charges of trafficking of a person for sexual servitude, deriving support from prostitution and keeping a house of prostitution, Algarin said by e-mail Wednesday.

"From what we've been able to determine about the operation thus far, it exploited numerous women, almost all of them immigrants," Algarin said.

"The women were expected to engage in sexual contact with multiple strangers for money that would go almost entirely to the defendants," she continued. "It's similar to other operations we've seen, in which the victims are not allowed to leave until they're rotated to another trafficking operation."

Federal officials, including members of the Immigration and Customs Enforcement agency known as ICE, and Boston Police officers obtained a federal search warrant and, on June 20, raided an apartment at 255 Cambridge St., where prosecutors said the prostitution operation was being run, Algarin said.

There, authorities seized: "large quantities" of cash; identification and immigration documents, some which were real and some which were fake; handcuffs; "multiple" phones and communication devices; and paraphernalia associated with prostitution, Algarin said.

During the search, Gallego allegedly “engaged officers in a violent struggle,” injuring two ICE special agents, according to Algarin. He has also been charged with two counts of assault and battery on a police officer.

Both men were arrested on the day of the search and detained, Algarin said. Formal criminal charges were filed against the men on June 28.

The search was part of a year-long, continuing investigation into an alleged human trafficking operation, she said.

One day after the search, Shawn Neudauer, a spokesman for ICE, responded to questions from the Globe by providing a brief statement describing the search as “a law enforcement operation in Boston” that involved special agents from ICE’s Homeland Security Investigations unit and officials from the Bureau of Alcohol, Tobacco, Firearms and Explosives and Boston Police. He and authorities from other federal and local law enforcement agencies, did not comment further until Algarin’s e-mail Wednesday.

Gallego and Agudelo are scheduled to return to court on July 15, Algarin said.