Hartford - Connecticut's second-highest court blasted a state prosecutor for repeated misconduct on Monday and ordered a new trial for a man serving life in prison for the killing of a Waterbury bar owner in 1998.

The Appellate Court overturned the murder and felony murder convictions of Victor Santiago, saying Senior Assistant State's Attorney Terence Mariani Jr. made improper comments during closing arguments to the jury.

But the judges didn't stop there. They concluded Mariani "has engaged in a deliberate pattern of improper conduct in this case and others."

"He remains undeterred by pronouncements by this court and our (state) Supreme Court that his conduct was improper," Judge Michael R. Sheldon wrote in the 3-0 ruling with Judges Richard A. Robinson and Bethany J. Alvord. "We believe that nothing short of reversal (of Santiago's convictions) will have the effect of deterring him."

Mariani, who works at Waterbury Superior Court, didn't return messages seeking comment Monday. His supervisor, Waterbury State's Attorney Maureen Platt, declined to comment on the Appellate Court's conclusions, but said Mariani is a respected and hard-working prosecutor who has tried an "utterly amazing" number of cases.

"He's tried some of the most significant cases in the state of Connecticut," Platt said. "I think he feels very strongly and deeply about his cases. ... I'm sure he's very saddened by the court's conclusions."

When asked if Mariani might face discipline, Platt responded, "Every time there is a decision on prosecutorial misconduct ... we take those decisions seriously and we do our level best to make sure those instances don't ever happen again."

Santiago, a reputed leader of the Latin Kings street gang, and his two brothers, Thomas Bonilla and Noel Bermudez, were arrested in 2010 in connection with the 1998 killing of Wilfred "Freddy" Morales outside his Waterbury home during a robbery. The killing went unsolved for a dozen years until Santiago's estranged wife implicated him. Bonilla and Bermudez were also convicted and are serving prison time.

The Appellate Court found that although the trial court limited evidence of Santiago's gang affiliation only to explain his wife's fear of him, Mariani "flouted" the ruling and made repeated references to the gang involvement. The court also said Mariani made "inexplicable" degrading comments about Santiago's wife and her children.

"We further note that Mariani's comments not only were improper in a legal sense, but they were also rude and irrelevant to any of the issues in the case," the court said.

Santiago's lawyer complained that Mariani improperly referred to her client as a "gang banger" and used his gang membership to attack his character and suggest to the jury that he was a violent person. The state conceded that the comments were improper because the judge had limited the gang evidence.

The Appellate Court said Mariani improperly appealed to the jury's emotions with his comments, and said he has done the same thing in many other cases.

Prosecutor Timothy Sugrue, who represented the state in Santiago's appeal, declined to comment. He said he was reviewing the decision and will be deciding whether to appeal to the state Supreme Court.

Santiago's attorney, Katherine Essington, didn't return a phone message Monday.