Employees in the Suffolk probate office, resentful of change and possibly motivated by racism, sought to undermine new Register Felix D. Arroyo when he assumed control of the office in 2015, according to an internal report obtained by the Globe.

At monthly staff meetings, some employees would ignore Arroyo and play with their phones or make “snide’’ comments about his Puerto Rican accent, claiming to not understand him, the report found.

“From the start of his administration, he was met with disrespect by the staff, both for his lack of knowledge of the court and his ethnic background,’’ retired Judge Anthony R. Nesi wrote in the April report, which has not been made public. “This lack of respect for him limited his ability to produce results.’’

The 66-page report was commissioned by the leaders of the Massachusetts Trial Court in February after they suspended Arroyo over allegations of mismanagement. It appears to substantiate his claims that he inherited an office with a severely reduced staff and a long, well-documented history of mismanagement.

But Nesi’s report also raised questions about Arroyo’s ability to improve the agency, which is under investigation by the US attorney’s office in Boston for potential civil rights violations.

“All told, he was unable to control or manage the staff effectively,’’ Nesi said.

Arroyo, who returned to work two weeks ago under an agreement with Trial Court officials, declined to comment on the report. His spokesman, Patrick Keaney, said Arroyo feels “vindicated’’ by Nesi’s findings.

“We have said from the beginning that Register Arroyo’s suspension was unjust,’’ Keaney said. “We have always maintained that Felix inherited an understaffed and dysfunctional office and that these problems were compounded by blatant racism and sabotage. The Nesi report confirmed that everything Register Arroyo said was true.’’

One government official with knowledge of the investigation said federal investigators are interviewing judges at the highest level, including Ralph D. Gants, chief justice of the Massachusetts Supreme Judicial Court, to learn more about the situation. The Suffolk Probate and Family Court, located in downtown Boston, handles a range of complicated legal and family matters such as adoptions, divorces, paternity cases, and name changes.

Officials have been interviewing court employees and are requesting personnel records to determine what percentage of employees are minorities, the official said. The official asked to remain anonymous because he is not authorized to speak publicly about the investigation.

The probe began after the Lawyers’ Committee for Civil Rights and Economic Justice in Boston urged the US attorney’s office to investigate the trial court system in light of Arroyo’s suspension.

Iván Espinoza-Madrigal, the group’s executive director, said he has interviewed 20 people who have complained of racism in other departments, including clerks who said they are undermined by other employees because of their race.

“We are urging the US attorney’s office to take a comprehensive look at the Trial Court, not just in connection with Mr. Arroyo but with what other employees of color are reporting as discrimination and reprehensible racism that goes unchecked,’’ Espinoza-Madrigal said.

For now, the federal investigation is limited to the Suffolk Probate Court, two government officials said. Trial court officials declined to comment on Espinoza-Madrigal’s allegations.

In a statement, Trial Court Chief Justice Paula Carey and Trial Court Administrator Jon Williams said they are “supporting Register Arroyo in the management of the Registry.’’

“To the extent there have been ethnic or racial tensions in the Registry, the Trial Court recognizes that the public elects registers to provide the necessary leadership for personnel matters in his office, including disciplinary action,’ they said.

Nesi’s investigation focused on how the office was run under Arroyo, who was accused of poor leadership that led to serious deficiencies in basic operations.

Scores of files disappeared, hundreds of thousands of dollars in checks went unprocessed, and the public was subjected to long wait times and rude treatment by some front desk staff, trial court officials said.

In his report, Nesi said many of those problems preceded Arroyo’s arrival but worsened on his watch for a “complex combination of factors.’’

The decline in performance “began before he took office,’’ Nesi wrote, “but continued and accelerated under his leadership.’’

Arroyo was elected in 2014, defeating Patricia Campatelli, who allegedly assaulted an employee after a holiday party. Campatelli never admitted any wrongdoing, arguing that she was a victim of unsubstantiated rumors.

An investigator found that Campatelli worked only 15 hours a week and spent much of it taking smoking breaks, playing scratch tickets, looking at East Boston real estate on the Internet, and doing puzzles.

Nesi found that Arroyo was an engaged register but made some questionable management decisions, such as standing by his first assistant register, a former campaign worker, even after he proved to be ineffective.

Although Arroyo made several attempts to ingratiate himself with staff, including removing the door to his office, his “good nature’’ made it easy for employees to get away with mistakes that someone with more experience in the workings of the Registry would have caught, Nesi said.

Older, white employees became resentful when Arroyo hired staffers of color who spoke second languages to work at the front desk and help visitors, many of whom are immigrants, Nesi found.

“There is no doubt that there were issues of racial name-calling and that there were racial tensions in the office, especially after new employees, who were minorities, were hired by Register Arroyo,’’ Nesi wrote.

Operations began to improve last October after court officials brought in Terri Klug Cafazzo, the first assistant register in Essex Probate and Family Court, to help run the Suffolk court, according to Nesi.

Keaney disputed Nesi’s description of Arroyo as inexperienced, saying he had managed employees in other settings for more than a decade of work.

“To ask anyone to produce outcomes with short staff, many of whom were openly racist toward Register Arroyo and their co-workers and actively sabotaged the work, is unreasonable,’’ Keaney said. “Instead of working with Register Arroyo to rectify this disturbing situation, the Trial Court suspended him and to date [has] done nothing about the members of the staff who were actively participating in sabotage and racism.’’

In their statement, Carey and Williams said they had recently invited the Equal Employment Opportunity Commission, the federal agency tasked with enforcing laws against discrimination in the workplace, to train staff at the court.

“The Trial Court will support Register Arroyo in taking appropriate disciplinary action for any violations of the Trial Court’s personnel and discrimination policies,’’ they said.

Maria Cramer can be reached at mcramer@globe.com.