SALEM – Two Revere residents pleaded guilty in Superior Court Thursday to bilking the Massachusetts Bay Transportation Authority out of an estimated $4 million in a massive scheme involving unauthorized rail passes they sold at a discounted price between 2007 and 2011.Judge Howard Whitehead sentenced Andres Townes, 28, of Revere to not less than three years in state prison on charges of falsifying books, larceny over $250 and conspiracy, and sentenced his accomplice Gloria Escobar, 28, to two years in the House of Correction on conspiracy and larceny charges.”This was the largest scheme in the history of the MBTA,” Assistant Attorney General Gina Masotta told the judge Thursday afternoon in Salem Superior Court. “[Townes] used a position of trust to execute the scheme, and it came at the expense of not only the MBTA, but also the taxpayers.”Townes worked for Cubic, a Beverly company that produces MBTA Charlie Card tickets, and modified a ticket-producing machine so that the MBTA would have no knowledge of tickets being printed.Townes produced more than 22,000 unauthorized tickets worth approximately $4 million between March 2007 and March 2011, Masotta said, and Escobar helped him sell the tickets at discounted rates to MBTA riders on Craigslist or over the phone.The investigation began on March 11 after an alert conductor on the Massachusetts Bay Commuter Rail (MBCR) noticed a pass that appeared different in color, according to a press release from the AG’s office.Masotta recommended that Townes receive five to seven years in state prison for the crimes, noting that Townes told investigators he estimated the scheme earned him between $600,000 and $800,000.Whitehead told the court the sentences reflected the seriousness of the crimes while also taking into account the pair’s lack of a criminal record.”These were not calculating people out looking to make money. There was just an irresistible temptation in front of them,” he said. “But it’s still a very serious crime. The public suffered and significant penalties are appropriate.”Townes’ attorney, William O’Hare, of Salem, said he hoped the sentence would be viewed as a “just and appropriate punishment.””Since the scheme was exposed, he’s been nothing but contrite,” he said. “He voluntarily met with investigators not once but twice on the day the warrant was issued, and more or less explained the whole process to them.”In April, a Suffolk Superior Court Judge awarded a $2.9 million judgment to the MBTA against Townes and Escobar.Townes’ sister, Joceline Townes, 42, of Boston, also pleaded guilty to receiving stolen property and conspiracy. Whitehead sentenced her to three months in the House of Correction, citing the fact that she did not begin participating in the scheme until December 2009.A fourth conspirator, Alex Saunders, 28, of Beverly, did not plea because his lawyer failed to appear at the hearing, but he is expected to plead guilty today.Taylor Provost can be reached at [email protected].