A Portland man accused of transporting a minor and two adults from Portland to Boston last summer to prostitute them has been arrested on a federal charge.

Samuel Gravely, 27, was taken into custody Tuesday in Portland on a warrant issued from U.S. District Court in Bangor on Monday on a charge of transportation in interstate commerce for prostitution.

An affidavit filed in Gravely’s case by Special Agent Anthony Castellanos of the Department of Homeland Security remained sealed, and few other details were immediately available.

A single-page criminal complaint accuses Gravely of transporting the minor and two adults to Boston on or about June 26 through June 29. Judge John Woodcock Jr. issued an order permitting the complaint to be made public.

The prosecutor, Assistant U.S. Attorney Gail Fisk Malone, has filed a motion to have Gravely detained, but no hearing date had been set for an initial appearance by Tuesday.

Gravely’s arrest comes just a day after multiple agencies, including the U.S. Attorney’s Office, gathered in Portland to announce a new initiative in Maine to identify and help victims of sex and labor trafficking. The initiative is funded by a new $400,000 federal grant to be administered over the next two years by Preble Street, a Portland social services agency.

State Rep. Amy Volk, R-Scarborough, has introduced legislation that would allow Maine’s state courts to vacate prostitution convictions to prevent women from being penalized for falling victim to human trafficking.