UPDATE: After this story was published, Boston city and police officials said on Friday Sgt. Det. Gallagher was removed from his role as the force's "Task Force Officer." He remains employed by the department. The audio atop this post aired Monday in Morning Edition.

There is a regular pattern of communication between Boston police and U.S. Immigration and Customs Enforcement (ICE) that includes emails regarding arrests for low-level offenses like trespassing and shoplifting, according to documents obtained by WBUR.

More than 800 pages of documents obtained by WBUR draw into question just how aligned the Boston Police Department's practices are with the public message coming from Mayor Marty Walsh's office — namely, that city police limit cooperation with ICE to only cases involving violent crimes and suspected felons.

'He Wants To Join Team America'

Walsh has been adamant that Boston police are not immigration officials and will not enforce federal immigration laws. And yet, an official conduit for cooperation does exist between BPD and ICE in the form of a single officer: BPD's ICE 'Task Force Officer." The TFO is a designated role trained to perform federal law enforcement duties.

In emails reviewed by WBUR, Boston police and federal immigration officials regularly offer information back and forth between the agencies. Often, the agencies are comparing arrest records of individuals accused of non-felony violations — like operating a vehicle without a license and shoplifting — to see if they have potential civil immigration violations, and vice versa.

In one such exchange from February, a deportation officer from Boston's ICE field office writes Boston Police Sergeant Detective Gregory Gallagher, BPD's designated ICE TFO. The ICE officer asks Gallagher for police reports on a woman and provides her name:

"I do not need prints. She has multiple Boston Larceny cases. She bailed out I would like to see if her parents names are located on any police reports. She appears to be a F-1 Student Overstay."

In his response, which BPD partially redacted, Gallagher provides a scanned copy of a booking sheet, which he tells the ICE agent includes the names of the woman's parents. It's unclear what action, if any, was then taken by immigration officials.

According to documents obtained by WBUR, Gallagher has offered to cover U.S. Department of Homeland Security (DHS) special agent shifts. He also occasionally receives requests for identity confirmation from federal immigration offices as far away as Texas.

Gallagher's role as a clearinghouse of information plays out in emails — both between him and U.S. immigration officials looking for criminal charges, and between him and fellow Boston officers looking to confirm suspected immigration violations.

In one exchange from February with BPD detective Juan Seoane, Gallagher is asked to verify a person's residency and immigration status. Seoane writes:

"He wants to join team America, but think he was part of a scam with his documents. Let me know, nothing urgent thanks."

Gallagher responds three days later, writing that "ICE checked it out" and the identity is authentic. It's not clear how the identity of the man came into question and whether he was wanted for a crime.

Local Police With Federal Authority

The flow of information between BPD and ICE largely stems from a contract signed in 2014 by then-BPD Commissioner William Evans and a former U.S. Homeland Security Investigations (HSI) special agent, Bruce Foucart. The agreement authorizes the designation of BPD employees to perform the roles and duties of customs officers, with limited exceptions.

More broadly, legal authority is granted to local and state law enforcement officers "to perform the full range of law enforcement duties of a Customs Officer" on behalf of ICE and HSI — an investigative arm of ICE. Designated law enforcement officers, again, known as TFOs, are trained in federal policies and law enforcement practices.

While TFOs are granted authority to make arrests for violations of federal law, they are not authorized to enforce administrative violations of immigration law — like overstaying a visa or living in the country without proper documentation.

ICE describes the local officers in these roles as supplemental to the agency's investigative mission, domestically and abroad. ICE officials did not respond to WBUR's repeated requests for comment on this story.

It was in this capacity that Gallagher received an email in March that included an ICE detainer as an attachment. Detainers are administrative warrants issued by ICE requesting local law enforcement continue holding a person who is otherwise free to go.

In the exchange, Gallagher was told the same detainer was also faxed to a court. Criminal and immigration violations are not laid out in the email; the sender is redacted. The message to Gallagher simply reads: "Happy hunting."

The state's Supreme Judicial Court ruled in 2017 that local law enforcement in Massachusetts do not have statutory authority to honor ICE detainers.

"A safe city is our first priority, which is why Boston Police will work with any state or federal authorities if criminal activity is in question for any resident in Boston," the mayor's office said in a statement Friday afternoon, adding that the city's officers "do not enforce federal immigration laws and that has never been the case."

The statement added that all federal law enforcement agencies have representatives from local police departments "to assist in criminal cases."

"And," the office continued, "we don't need to look any further than at the large-scale sweeps to get guns out of our neighborhoods or the Boston Marathon bombing for why these partnerships are critical to a safe city."

Boston Police Commissioner William Gross told WBUR Thursday that his officers are focused on violent crimes and drugs, not a person's immigration status.

In email correspondences reviewed by WBUR, 30 designated TFOs were notified in February about upcoming training with HSI in Boston. In addition to Gallagher, the list included an MBTA officer, a Bristol County sheriff's sergeant and other state and local officials throughout New England.