Eng did not offer a timeline for when the investigation began or what led the T to begin looking at the facility, located in the shadow of Interstate 93 on Dorchester Boulevard in South Boston. This is where Red Line maintenance happens and accomplishes its mission. Home base for Red Line inspectors and workers maintaining the Red Line route.

“As public servants, we have an obligation to fulfill the duties we accept in our roles,” Eng said. “Apparently these employees were not doing this. “Apparently they were doing something they shouldn’t have been doing on MBTA property or on MBTA time.”

T’s human resources department and labor relations team began investigating, Eng said. Transit Police then took over the investigation.

Eng’s comments on Thursday confirmed publicly for the first time where the investigation was focused.

“We want to fully investigate this. We know how important this is, not only for what we want to do, but also for public trust,” Eng said.

MBTA police did not respond to multiple requests for comment. Massachusetts State Police deferred comment to the Suffolk district attorney’s office. A spokesman there said this week that the office was not involved in any investigation. A Boston police spokesman said they were unaware of any recent arrests connected to Cabot Yard. A spokesperson for MassDOT referred comment to the MBTA. A spokesman for the state Attorney General’s Office and the U.S. Attorney’s Office said they could neither confirm nor deny the existence of any investigation, as is typical policy.

Multiple messages left for the Boston Carmen League were not returned this week. A union representative declined to comment before hanging up the phone.

The investigation marks the latest controversy over the T, a recently maligned institution. metro line delays, train derailments, Employee negligence claimsAnd equipment malfunctions.

Several T employees who entered Cabot Yard this week refused to talk about what was happening, saying they were not supposed to talk to the press.

Shannon Larson can be reached at [email protected]. follow him @shannonlarson98. Sean Cotter can be reached at [email protected]. follow him @cotterreporter. Danny McDonald can be reached at [email protected]. follow him @Danny__McDonald.