The promoter of the Boston Calling music festival, aided by a former top campaign adviser to Mayor Martin J. Walsh, lobbied indicted city tourism czar Kenneth Brissette to quash a rival music event that later fell apart due to a lack of city support, a Herald investigation shows.

“Please kill it if you can,” Boston Calling organizer Brian Appel told Brissette in an April 29, 2015, email.

Appel got his wish — the proposed Sea by Sound hip-hop festival, which had been slated for September, the same month as Boston Calling, died after Brissette and other city officials abruptly stopped assisting the promoters.

Emails reviewed by the Herald also show Boston Calling’s consultant, Chris Keohan, who worked on Walsh’s 2013 campaign with Brissette, passed along a confidential “investor deck” to the tourism chief revealing the hip-hop festival’s marketing strategy and planned dates in September.

Keohan and Appel were both concerned that the investor deck claimed the city of Boston was a partner.

“Do you know what this is?” Keohan wrote to Brissette, who then sent an email to Crystal Torman, an aide to Chief of Economic Development John Barros, saying, “We need to talk to this person.”

Torman did schedule a meeting a week and a half later but it was cancelled at the last minute when Brissette was a no-show. Torman then didn’t respond to the promoters’ repeated requests for a meeting.

Brissette actually intervened a month before that, when he became aware of Sea by Sound’s plans. He called one of the festival promoters, Sidney Baptista, angrily upbraiding him for not dealing with his office, according to Baptista’s business partner Randall Harris.

“Who the (expletive) are you?” he told Baptista, according to Harris.

Brissette also had another city official call Baptista to tell him to stop using information from a city website in its promotion materials.

The rival festival was designed to showcase local hip-hop artists and draw a younger and more diverse audience than Boston Calling. Harris said he felt the city was fully behind the idea and didn’t know why officials stopped helping them.

“We followed up a bunch of times and they sort of went ghost,” Harris said in an interview. “We had heard Boston was a hard place to bring events like this.”

Brissette was indicted last month on extortion charges, but Walsh has defended him and the tourism chief continues to get his $102,000-a-year salary. The U.S. Attorney’s Office alleges Brissette withheld permits for Boston Calling until Appel hired local union stagehands for its show on City Hall Plaza

Brissette’s emails, obtained by the Herald in a public records request, show Keohan frequently asked for Brissette’s help on Boston Calling and the planned IndyCar race, which the Walsh adviser also represented.

Brissette usually was eager to comply, emails show.

Brissette also was in contact with Kate Norton, Walsh’s former press secretary, who joined Keohan’s firm in January 2015. Appel and Keohan both sent emails to Brissette on April 29 expressing concern about Sea by Sound and its claim the city was backing it.

“I’m just checking to see if this event is going to happen/get approval or if it’s not,” Appel wrote to Brissette. “Looks like the city of Boston is a partner? It shapes our planning a little bit.”

Brissette responded: “I have no idea what it is and trying to find out.”