A Portland man convicted of prostituting women testified in federal court in Portland on Monday in the trial of a Boston man accused of being his criminal mentor, saying the defendant told him the illegal sex trade was “the new way” to make money in addition to selling drugs.

The Boston man, 29-year-old Fritz Blanchard, is on trial in U.S. District Court on a charge that he and the convicted Portland man, Samuel Gravely, took three young women from Portland to Boston on March 28, 2013, to prostitute them.

Gravely, 28, is being held at the Cumberland County Jail in Portland after pleading guilty on Nov. 20 to charges against him. Blanchard, however, has denied any wrongdoing and pleaded not guilty to a charge of transportation in interstate commerce for prostitution.

Blanchard had been scheduled to reverse his plea in a hearing May 5 before U.S. District Judge Nancy Torresen, but changed his mind and opted for a trial this week instead. The trial is scheduled to take about four days.

Gravely was the first witness to testify Monday, telling a jury of 11 women and two men how Blanchard encouraged him to advertise his girlfriend from Presque Isle on a website for prostitution, and accompanied Gravely and the girlfriend when they pimped her twice in Bangor in March 2013.

“He knew a new way to make money besides just selling drugs,” Gravely said of his conversations with Blanchard in 2012 and 2013. “He told me that prostitution was the new way, that there was money to be made in it.”

Gravely testified that he and Blanchard grew up together in the Dorchester neighborhood of Boston but had lost touch with each other after Gravely was convicted in Massachusetts of illegal gun possession in 2003 and in two drug dealing cases in 2004 and 2005. After serving time in a Massachusetts prison, Gravely moved to Maine and the two reconnected in 2012.

Blanchard is accused of driving with Gravely, Gravely’s girlfriend, and two other women they met in Portland – an adult and a juvenile – to the Midtown Hotel in Boston.

The prosecutor in the case, Assistant U.S. Attorney Gail Fisk Malone, said in her opening statement Monday that the trip from Maine to Massachusetts was “very well documented,” with cellphone photographs, rental vehicle records, bank records, hotel check-in records and video footage.

“The real question for this trial is: What was the defendant’s intention when he transported the three women from Portland to Boston?” Malone said.

Blanchard’s attorney, Joel Vincent, agreed with Malone that the central issue in dispute is Blanchard’s intent during the trip and whether he intended to prostitute the women in Boston.

“Mere presence when someone else is committing a crime is not a crime,” Vincent said in his opening statement to the jury.

Gravely testified that he drove his girlfriend, Blanchard and the juvenile girl from the hotel to “the track,” a strip on Harrison Avenue in downtown known for prostitution.

Gravely’s girlfriend, who testified as the second witness in the trial, said that Blanchard told her when they got to the Boston hotel not to tell the juvenile girl that they were prostitutes. But she said that Gravely, whom she knew by the nickname “Bigs,” told her to explain to the juvenile girl what was happening.

The Press Herald is not identifying the women or the juvenile because they are considered victims in the case and have not been charged with any crimes.

Gravely’s girlfriend testified that the juvenile girl was suffering from symptoms of opiate withdrawal on the drive to Boston and began crying when the men would not get her drugs.

Malone said she planned to call the other women to testify at the trial, as well as the hotel manager, a Boston police officer and a Portland police officer.

Malone said she expects witnesses to testify that the juvenile girl did not know she was expected to be a prostitute when she first got in the car with the men, feigned illness and slipped away to call police from the Boston hotel.

If convicted, Blanchard faces up to 10 years in prison and a fine of $250,000. Gravely, who faces the same penalty, is scheduled to be sentenced on Sept. 23.