HARTFORD, Conn.—A Connecticut man found guilty of killing four people failed to convince the state Appellate Court that his convictions should be thrown out because he was referred to by his nickname—"Killer"— at trial.

The use of the nickname was "inappropriate," but Marco Camacho failed to prove it prejudiced the jury enough to warrant a new trial, the state's second-highest court said Monday.

Camacho was convicted in the 1996 murders in Southington of Nick Votino, 50; Joanne Votino, 18; and their house guests, Lynn Suszynski, 26; and Wayne Barrows, 44. Prosecutors said he and an accomplice, Erik Lee Henry, went to the house to collect a $400 drug debt from Nick Votino. When they were not paid, Camacho became enraged and shot everyone inside, they said.

Camacho, who was 17 at the time of the murders, was convicted of felony murder in 2002 and sentenced 260 years in prison. Henry received a 45-year prison sentence after pleading guilty to murder and a drug charge.

In Camacho's latest appeal, his lawyer, Joseph Visone, argued the jury was prejudiced not only by the use of the nickname but by the cumulative effect it had on jurors when combined with the playing of a 911 tape.

The "Killer" nickname was used twice by Henry's girlfriend, who was called to the stand by prosecutors—once during her initial testimony and again, six weeks later, when she returned to the stand.

Defense lawyers asked for a mistrial both times and were refused. The trial judge did caution the jury to disregard the nickname.

The 911 call was made by Joanne Votino after she was shot. On it, she can be heard gasping for breath. Prosecutors played it during the evidence portion of the trial and again during closing arguments.

In an email Monday, Visone said he would file a petition seeking another review by the state Supreme Court.

That court rejected Camacho's initial appeal in 2007. In that appeal, he unsuccessfully argued that his trial judge should not have allowed hearsay testimony by Henry's girlfriend and another woman about what Henry told them about the killings.

Henry did not testify at Camacho's trial because he invoked his Fifth Amendment right against self-incrimination.