Prosecutors say Bunn was a recruited by the leader of a gang to shoot Gamble, who he believed had told police where to find another gang member.
Bunn was one of three people charged, but prosecutors say he was the gunman. The other two testified for the prosecution.
Bunn denied shooting Gamble, saying it was one of the others.
Bunn, tried as an adult, will be eligible for parole in 28 years.
Information from: New Haven Register, http://www.nhregister.com
Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.