An appeals court is considering whether misconduct by Suffolk prosecutors resulted in a Wheatley Heights men getting convicted improperly for the 2009 murder of a Wyandanch man.

If the Second Department of the Appellate Division decides that Rudolph Bisnauth, now 31, did not get a fair trial in 2012, it could overturn his second-degree murder conviction. Bisnauth was found guilty of taking part in the fatal shooting of Jeremiah Armstrong, 37. Another man, Michael McKenzie, 30, pleaded guilty to first-degree manslaughter in the case.

Prosecutors say the two men sprayed the front of Armstrong’s house with gunfire after a friend of theirs, Timothy Rich, had a dispute with Armstrong’s daughter. Rich and the daughter had a child together, but she broke up with him and canceled the insurance on his car after she found out he was engaged and living with another woman, according to court papers. Friends of Armstrong’s daughter threatened Rich and he responded by calling her and warning her to get out of the house before the shooting.

Bisnauth’s appellate attorney, Joseph Ferrante of Hauppauge, argued Tuesday in Central Islip that lower courts allowed prosecutors to violate his client’s rights in several ways.

One was not telling Bisnauth’s trial attorney that Rich, who testified at the trial, was an informant on drug cases at the time of the crime. Under what is known as the Brady rule, prosecutors are generally required to turn over any evidence to defendants that could be helpful.

If Bisnauth’s trial attorney had known about Rich being an informant, Ferrante said it would have been a devastating weapon in cross-examining Rich during the trial. He would have been able to ask both Rich and detectives if the reason he wasn’t charged was to protect drug investigations.

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“He was the glue that held the whole thing together,” Ferrante said. “He started the fight. He showed his boys the house.” And detectives testified Rich was a suspect in the killing.

After the trial, state Supreme Court Justice Mark Cohen found that prosecutors had violated the Brady rule by not telling the defense about Rich’s status as an informant, but ruled it would not have made a difference in the verdict. Ferrante disagreed, in part because he said the case was not so clear-cut.

Assistant District Attorney Michael Miller didn’t dispute the Brady violation but argued that Rich’s credibility was not important to the case. He said there was no evidence that Rich ordered the shooting or took part in it in any way. “You could try this entire case without him,” Miller said.

Ferrante also argued that the trial prosecutor, Assistant District Attorney Robert Biancavilla, questioned two witnesses improperly. The law generally does not allow attorneys to challenge the credibility of their own witnesses, but Ferrante said Biancavilla did that twice when prosecution witnesses did not testify that the gun jammed while McKenzie was firing it.

Biancavilla confronted those witnesses with earlier statements they made, in which they said the gun jammed and that Bisnauth unjammed it before the shooting resumed.

That should never have been allowed, Ferrante said, adding: “What’s the point of the rule if it’s not going to be followed?”

Some of the appellate judges suggested there was no basis for Biancavilla to undermine his own witnesses.

“Where in the world do we even remotely have the need to refresh these witnesses’ recollections?” Justice Leonard Austin asked Miller. “He never said he didn’t remember [what happened] and the [trial] court bought into it.”

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Miller said the gun jamming and Bisnauth unjamming it was a critical part of the case, so Biancavilla was justified in pushing the witnesses to testify about it.

“That’s the issue in this case,” Miller said. “That was the people’s case.”

The court is expected to rule in a few weeks.