A seemingly obvious question never arose at the 1999 armed robbery trial that landed Vernon Boudreaux a 30-year prison sentence.

The robbery victim and lone eyewitness, former New Orleans Police Department homicide Detective Glenn Taylor, had left the force about 18 months earlier.

But unknown to Boudreaux’s attorney or the jury, Taylor’s departure was far from voluntary.

He was fired for wrapping a dog’s choke chain around the neck of his estranged wife, dragging her around the house and then lying about it to investigators, records show.

The NOPD also found he had repeatedly double-dipped by working an off-duty detail at the Superdome while clocked in with the homicide squad.

Whether Orleans Parish prosecutors were obliged to dig up that information from public civil service records and turn it over to Boudreaux’s attorney — and whether it would have changed the outcome of the trial — took center stage at a hearing this past week on his bid for a new trial.

A prosecutor for District Attorney Leon Cannizzaro’s office didn’t quibble with a claim by Boudreaux’s attorneys that Taylor’s dishonesty as a police officer would have cast his credibility in doubt. But Assistant District Attorney Kyle Daly said there was no evidence that then-prosecutor Lionel “Lon” Burns knew about Taylor’s sacking.

Daly argued that Boudreaux’s attorney at the time, public defender Dennis Moore, could easily have found Taylor’s civil service record himself and that then-District Attorney Harry Connick’s office had no legal obligation to do his homework for him.

With help from the outside, Boudreaux, now 54, found the public documents in 2012, leading to his latest challenge to his conviction.

Taylor, who enrolled at Dillard University after his firing, identified Boudreaux as one of two men who held him up at a Walgreens drugstore on Gentilly Boulevard and drove him at gunpoint to Humanity and Spain streets, robbing him of more than $60.

At the trial, Burns and another prosecutor made note of Taylor’s history as a police officer, aiming to burnish his credibility as a witness. The last chapter, however, was missing.

Burns insisted he never spoke with Taylor before the trial.

As a prosecutor, Burns once was found in contempt of court for failing to turn over evidence that appeared by surprise in the third rape trial of a former cop in 2000. Now a criminal defense attorney, Burns sought to unseat Cannizzaro as district attorney in 2014 before a court disqualified him over tax issues.

Katherine Mattes, director of the Tulane law school’s Criminal Litigation Clinic, which is representing Boudreaux, pressed Burns on Tuesday about the importance of the information about Taylor’s firing.

“Evidence that a police officer was fired for lying to an investigating officer would be relevant to that witness’s credibility, would you agree?” Mattes asked.

“No, I wouldn’t agree with that,” Burns responded. “A lot of times we have New Orleans police officers who are arrested and indicted for payroll fraud. Does that mean we turn around and (conclude) in every single case those police officers have been a part of, that it was a bad arrest? Of course not.”

Moore, Boudreaux’s trial attorney, testified that he was led to believe Taylor left the force to attend Dillard.

“They knew he was their main witness, their only witness, and they did not turn it over,” Moore said of the civil service record.

Taylor was expected to testify Tuesday, and he sat in the courthouse hallway but was never called to the witness stand.

At issue for Criminal District Court Judge Laurie White is whether prosecutors violated U.S. Supreme Court rulings that require the state to turn over all evidence favorable to a defendant, including evidence that concerns the credibility of a government witness.

By law, prosecutors can’t claim ignorance when it comes to records kept by police. Boudreaux’s attorneys argued the same goes for civil service records.

“In order to convict Mr. Boudreaux, the jury had to believe Glenn Taylor, and yet the NOPD’s own assessment was that Glenn Taylor was not credible,” said Anton Martynenko, a student lawyer for the Tulane clinic who argued it was a failure by the state that hurt Boudreaux at his trial.

Daly, however, cited a Louisiana Supreme Court ruling from 2010 that says prosecutors don’t need “to furnish a defendant with information he already has or can obtain with reasonable diligence.”

White expressed skepticism.

“With that logic, it would behoove every prosecutor not to find out that much about their case because they could say, ‘We don’t have that obligation. You’ve got to find it,’ ” the judge said.

Daly, the assistant district attorney, called it a “fair point,” then added, “I suppose a prosecutor willing to take that risk could possibly do it. I’m not saying it’s good practice, but it seems like that’s what happened in this case.”

White did not immediately rule, asking both sides to submit written briefs.

Follow John Simerman on Twitter, @johnsimerman.