A federal grand jury is investigating the alleged theft of overtime pay and other misconduct involving members of the Massachusetts State Police, according to multiple people with knowledge of the criminal probe.
Prosecutors are examining whether members of Troop E — the unit that until recently patrolled the Massachusetts Turnpike — committed fraud by collecting pay for overtime shifts they did not work, and whether supervisors were aware of or participated in the practice, the people said.
Dozens of current and former Troop E members have been linked in recent months to the alleged pay scandal, resulting in a wide-scale audit, a series of internal State Police investigations, a separate probe by the attorney general's office, and the disbanding of the entire unit. Records show some troopers reported earning five- and six-figure overtime payouts.
Two of the people with knowledge of the inquiry said federal investigators are also looking more deeply at the agency, including alleged wrongdoing outside Troop E.
In recent days, federal prosecutors issued subpoenas to several current and retired troopers from Troop E.
Two Troop E members in Western Massachusetts — Sergeant Jason Sternfield and Sergeant Michael Lynch — received orders to appear June 7 before a federal grand jury in Worcester, according to a person familiar with the investigation.
Their attorney, Brian E. Burke, said the sergeants did nothing wrong.
"We'll find out what it is [about]," Burke said. "But they have nothing to hide. They are decent guys who got caught up in something they had nothing to do with."
Sternfield and Lynch are not among the dozens of troopers implicated by State Police.
A spokeswoman for US Attorney Andrew Lelling declined to comment. State Police spokesman David Procopio said the agency would not confirm or comment on a federal criminal probe.
"We can speak only of our own investigation, which we are undertaking to ensure that any department member who received payment for hours they did not work is held accountable and subject to appropriate disciplinary action," Procopio said.
A state criminal investigation, led by Attorney General Maura Healey's office, is ongoing. An office spokeswoman declined to comment further.
News of the federal probe is the latest problem for the State Police, which has been roiled over the past year by a series of scandals including hidden payroll at Logan Airport, the alteration of an arrest report for a judge's daughter, and allegations of widespread overtime abuse.
On Friday, Colonel Kerry Gilpin announced five more troopers from Troop E would be called in for hearings next week because of "alleged discrepancies between overtime pay received and hours worked."
The hearings will determine whether the troopers will be suspended with or without pay, or allowed to remain on the job, while the allegations are investigated.
These troopers are in addition to 28 active or retired members of the force who are already under investigation for fraudulent overtime payments.
Former colonel Richard McKeon launched an audit of overtime pay last fall — before he abruptly retired amid accusations he forced troopers to remove embarrassing information from a police report involving the daughter of a Dudley District Court judge.
Gilpin, who was appointed to the job in November, expanded the investigation.
Troopers allegedly used a variety of methods to inflate their overtime pay, according to several troopers and attorneys. Troopers allegedly falsified dates and times on tickets to claim they were working overtime.
The practice, according to troopers and attorneys, was widespread and took place over several years.
State Police officials referred the matter earlier this year to Healey's office.
The US attorney's office has broad discretion to investigate possible incidents of wire or mail fraud, or embezzlement. If convicted of mail or wire fraud, a defendant can face up to 20 years in federal prison.
A separate federal fraud investigation landed a Quincy police lieutenant in prison last year. Thomas Corliss was sentenced to a year for bilking the city of $8,000 by filing for paid details and shifts that overlapped. He was convicted of mail fraud and the embezzlement of federal funds.
His attorney, Robert Sheketoff, said the federal mail and wire fraud statutes are broad and can be used to prosecute crimes that typically would be considered state offenses.
All prosecutors have to prove is that wires or the mail were used as part of the fraud, Sheketoff said. He said he didn't think it was unusual for the US attorney's office to launch an investigation into the State Police overtime scandal.
"It strikes me as appropriate for both the attorney general and the US attorney to think state law enforcement agencies are more appropriately prosecuted by the feds than other state actors that have really strong working relationships," Sheketoff said.
The State Police overtime scandal first surfaced last year when Trooper Eric Chin was suspended for allegedly abusing overtime while working radar patrols on the Mass. Turnpike.
WCVB-TV first reported that four lieutenants and a trooper were paid for more than 100 overtime shifts targeting dangerous drivers where no speeding tickets were written.
Chin spoke out publicly and said overtime abuse was common among both rank and file troopers and their supervisors.
Governor Charlie Baker and Gilpin in April announced they would eliminate the Troop E unit and begin tracking cruisers through GPS monitoring.
The State Police Association of Massachusetts, the union that represents troopers, has opposed the measure.
In early May the union filed a complaint with the Massachusetts Department of Labor Relations accusing the agency of acting in bad faith by not giving the union a chance to negotiate the decision to implement vehicle tracking.
Needham attorney Timothy Burke, who represents a number of State Police lieutenants and captains, said none of his clients has received a subpoena from the US attorney's office or the state attorney general's office.
"I can say that I am aware that both agencies are conducting an investigation," Burke said. "I think essentially it's just a wait and see what the subject matter is and whom, if anybody, they are looking at."
Andrea Estes can be reached at Andrea.Estes@globe.com. Shelley Murphy can be reached at email@example.com.