Three people have been indicted for allegedly running brothels that sold women for sex throughout Greater Boston, officials said.

The three suspects, Pingxia Fan, 40, of Boston; Timothy Hayes, 50, of Gloucester; and Simon Shimao Lin, 59, of Boston, were indicted Thursday by a statewide Grand Jury on human trafficking and money laundering charges, the office of Attorney General Maura Healey said.

The three were arrested in May following a joint investigation of the alleged crimes. The attorney general's office started its investigation after a referral from the North Reading Police Department, which did an initial investigation into a residence in their town.

The defendants are accused of arranging for women to meet with men at brothel locations -- two in Quincy, and single locations in Boston, Cambridge, and North Reading -- to provide commercial sexual services in exchange for cash, Healy's office said in a statement.

Authorities say the majority of the money from the encounters went to the defendants, which was laundered into the business for daily operations of the criminal enterprise, the statement said.

Prosecutors previously said that Asian women were transported to Massachusetts from Flushing, New York, to offer sexual services.

Apartments were used as brothels, prosecutors say, with two or three women working in each residence. The spaces were sparsely furnished, with some only featuring mattresses on the floor.

Customers were charged $100 for 15 minute appointments, according to court documents, raking in more than $100,000 a week.

"Collectively, it's estimated that Fan and her associates were making millions of dollars, every year, exploiting women," said Harold H. Shaw, the special agent in charge of the FBI Boston Division. "When human beings are treated as commodities and are trafficked for sex, they are not only being abused physically, but emotionally, mentally, and financially."

The defendants allegedly used multiple vehicles to transport sex trafficking victims, money and supplies.

The three are scheduled to be arraigned in Suffolk Superior Court on some charges on July 18. They will be arraigned in Middlesex and Norfolk Superior Courts at later dates.

"Victims of human trafficking are preyed upon by pimps and traffickers who exploit the most vulnerable among us for profit," said Healey. "We allege these defendants ran an extensive criminal operation that took advantage of women and sold them for sex."

Hayes and Fan were indicted on five counts of trafficking persons for sexual servitude; five counts of deriving support from prostitution; five counts of keeping house of ill fame; five counts of conspiracy to traffic persons for sexual servitude; and three counts of money laundering.

Lin was indicted on two counts of trafficking persons for sexual servitude; two counts of conspiracy to traffic persons for sexual servitude; and three counts of money laundering.