The defense attorney hired by Mayor Martin J. Walsh to represent his administration in a federal investigation of a union's alleged extortion scheme will be paid $625 an hour, according to a contract released Friday.
That rate is nearly three times what the city usually pays outside lawyers.
The attorney, Brian T. Kelly, is a former federal corruption prosecutor enlisted by Walsh after City Hall was mentioned in a criminal indictment accusing members of Teamsters Local 25 of trying to force the television show "Top Chef" to abandon its nonunion crew. Kelly, now a partner at Nixon Peabody, is working for a discount but will still be one of the highest-paid outside lawyers hired since Walsh took office.
"The city received a reduced rate to retain attorney Kelly's services and we expect attorney Kelly's work to be swift but comprehensive," Walsh's spokeswoman, Laura Oggeri, said in an e-mail. "Mayor Walsh believes that attorney Kelly will be able to provide an objective review as to what happened and facilitate any necessary cooperation between the city and the US attorney's office."
Unlike other city legal contracts, the agreement did not set a cap limiting the total cost. The contract runs through the end of the fiscal year, June 30, 2016. In an interview, Kelly said it was not clear how many hours the case will require.
"I'll make every effort to be as efficient as possible," Kelly said.
Walsh has previously said Kelly will investigate "to make sure that the city has done everything correctly." But the mayor has not pledged to make all of Kelly's findings public, and his work appears to be exempt from the open records law because of attorney-client privilege. His fee will be covered by taxpayers.
On Friday night, Oggeri said in an e-mail that "pending any legal or other issues, a summary of [Kelly's] report will be made public."
The contract, which the Globe requested at the beginning of the month, was dated Oct. 14. It stipulated Kelly's hourly rate and noted that his associate, Charles Dell'Anno, will be paid $285 an hour.
The Walsh administration said Kelly has begun his work, but officials were unable to provide the average number of hours per week because it varies, Oggeri said.
The city has its own cadre of lawyers headed by Eugene L. O'Flaherty, Walsh's longtime confidant who serves as the city's corporation counsel.
"There are going to be times when the city has to go outside for legal representation for a level of expertise they don't have in house," said Samuel R. Tyler, president of the Boston Municipal Research Bureau, a fiscal watchdog underwritten by businesses and nonprofits. "I would think that because this is public money that the information would be made public. At least it should be."
A Globe review of contracts found that the city hires scores of outside attorneys to handle a variety of matters. One significant contract has gone to Thomas C. Frongillo, a high-powered attorney handling the Walsh administration's legal fight to stop casino mogul Steve Wynn from building a gambling resort in neighboring Everett.
Frongillo is paid $490 an hour. His fee reflects a discount of roughly 50 percent from his regular rate. Through August, the bill topped nearly $1.3 million.
At $625 an hour, Kelly will not be the city's highest-paid outside counsel, Oggeri said. The city has hired bond attorneys at a higher rate, Oggeri said, although she did not provide specifics.
The Teamsters' arrest last month cast an unwanted light on City Hall. Five members of the union are accused of harassing and intimidating the television production crew with what US Attorney Carmen Ortiz called "old school thug tactics'' that reflected "poorly on our city.''
The indictment said an unidentified member of Walsh's administration made phone calls to a hotel and restaurant to warn the establishments that Teamsters would picket if the establishments hosted film crews that included nonunion workers.
The identity of the City Hall caller has not been publicly disclosed, and Walsh has said he does not know who called the businesses.
The Globe previously reported that two people familiar with the investigation identified the caller as Kenneth Brissette, the Walsh administration's director of tourism, sports, and entertainment. Brissette has not returned phone messages seeking comment.
Brissette has continued working at City Hall. Neither he nor any other city employees have been disciplined or fired in connection with the alleged extortion scheme, Oggeri said.