A second city official has been indicted in connection with the alleged extortion of a local music production company.

Federal investigators arrested Boston’s Chief of Staff of Intergovernmental Affairs Timothy Sullivan early Wednesday on a two-count indictment charging him with conspiracy and extortion, U.S. Attorney Carmen Ortiz said.

Sullivan, 36, appeared in federal court hours later, and was released on $25,000 unsecured bond.

Related:  Boston tourism chief arrested on extortion charges

His arrest follows that of Kenneth Brissette, 52, who was arrested in May in connection to the extortion case. Brissette worked as Mayor Marty Walsh's director of tourism and was indicted for allegedly extorting a company which had already contracted with a non-union company to provide workers for a September 2014 music festival.

Investigators claim that between July and September 2014, while the company was awaiting the issuance of certain permits and approvals required for its music festival, Brissette and Sullivan repeatedly advised the company that it would need to hire members of Local 11 to work at the music festival.   Local 11 had attempted to obtain work from the company since March 2013.

  The company told Brissette and Sullivan that it had already entered into a contract with a non-union company and hired all of its labor, Ortiz said.   But Brissette and Sullivan allegedly insisted that half of the company’s labor force consist of union members, although they ultimately agreed that eight members of Local 11 would suffice.

As a result of their demands, Ortiz said, three days before the music festival the company entered into a contract with Local 11 for eight additional laborers and one foreman.   Shortly thereafter, Boston issued the necessary permits.

Though the Boston music festival is not named in the indictment it is widely acknowledged to be Boston Calling.

Following the news of Sullivan's indictment, Walsh released a statement saying he was “deeply concerned about the allegations.” Walsh said he had called for an independent ethics-training program for all of the city's department heads.

“It is a great privilege to serve in City Hall and I will not allow anyone to squander that privilege,” Walsh said. “I expect everyone to perform at the highest ethical standards. There is no room in my administration for the type of behavior that is alleged here.”

Walsh said he also had outside counsel looking into how these events have been managed.

“We are having a panel of experts review how things are done and help improve policies. I will not pre-judge anyone's guilt or innocence. Nor will I tolerate anything less than the highest ethical standards.”

Ortiz said Wednesday's indictment is a superseding indictment, which added two counts against Sullivan and one more count against Brissette.

Sullivan’s arraignment was set for July 12.