Attempts by Orleans Parish District Attorney Leon Cannizzaro’s office to hold Irvin Darensbourg Sr. accountable for other alleged crimes despite his acquittal this year in the 2010 killing of a teenager appeared to fall flat this week.

Retired Judge Dennis Waldron, who is sitting ad hoc over the case, on Wednesday tossed out the additional charges against Darensbourg related to the 7th Ward shooting that killed Trevon Tanner, 17, and wounded two others. Over objections from prosecutors, Waldron then ordered Darensbourg’s release Thursday.

Cannizzaro’s office filed an emergency writ with the Louisiana Supreme Court, asking it to keep Darensbourg behind bars on a high bail while an appeals court hears arguments on whether he can still face a conspiracy count and two counts of attempted murder related to the shooting on April 11, 2010, in the 2600 block of D’Abadie Street.

A decision from the state’s highest court was pending Thursday night.

The 4th Circuit Court of Appeal on Thursday rejected the same plea to keep Darensbourg jailed while it weighs the issue. So Waldron refused to wait, saying Thursday he had no choice but to release Darensbourg.

The 22-year-old was accused of plotting the murder of Tanner, then firing the bullets that killed Tanner and hit two others.

Prosecutors said Darensbourg plotted with two other men, LaJuan Thomas and Kevin Thomas Jr., to kill Tanner — who had been shot before and had identified LaJuan Thomas as his assailant — to stop him from testifying.

The plan worked, prosecutors argued. LaJuan Thomas, who was in jail when Tanner was shot in the head as he sat on a porch at D’Abadie and Paul Morphy streets, went free afterward.

A grand jury in early 2011 indicted Darensbourg on a count of first-degree murder, a count of conspiracy to commit murder and two counts of attempted murder.

After securing plea deals from the other two defendants, Cannizzaro’s office reduced the murder charge against Darensbourg to second-degree and tried him separately on that count, intending to save the other counts for later. A jury acquitted him in April after a trial before Criminal District Court Judge Julian Parker, who has since left the bench.

Waldron agreed with Darensbourg’s attorneys on Wednesday that the remaining charges against him should be quashed because the jury had weighed evidence of a conspiracy and also of the two alleged murder attempts before acquitting him.

Waldron cited the doctrine of “collateral estoppel,” a concept normally used in civil court to prevent relitigation over the same evidence. While not technically “double jeopardy,” the reasoning left the same result: dismissal of the other charges against Darensbourg.

“The prosecutor did concede ... that she did present some evidence of the alleged conspiracy” at the murder trial, Waldron said in a written opinion. “Also, the jury heard evidence of the two attempted murder charges.”

Eric Malveau, one of Darensbourg’s attorneys, said Darensbourg was due to be released Thursday night, barring a stay by the Supreme Court.

“It’s clearly a jury’s verdict. They heard everything. They heard he supposedly conspired with these other guys to commit the murder. They heard he supposedly pulled out the gun, shot it, killed the guy. They heard from a witness who said she was present when the murder was planned, evidence of the planning,” Malveau said.

“They acquitted him. That’s what the system is based on. The jury sits in a box, they hear the testimony and they make a decision. That’s the way the cookie crumbles.”

Christopher Bowman, a spokesman for Cannizzaro’s office, noted that the appeals court has yet to rule on Waldron’s decision to quash the remaining counts against Darensbourg, deciding Thursday only that it wouldn’t halt his release.

“We feel that Judge Waldron erred in his ruling and that the charges that were severed from the original trial remain viable charges,” Bowman said. “We are going to take every shot allowed by law against people who commit violent crimes on the streets of New Orleans.”

Bowman added that prosecutors “respectfully disagree with the jury’s verdict in the case, but we’re moving forward.”

Follow John Simerman on Twitter, @johnsimerman.