Federal prosecutors in the Jefferson Parish “sniper van” case hit back Wednesday against a defense claim that investigators searched the suspiciously outfitted vehicle without a warrant, saying authorities were legally required to take inventory of the van before it could be towed.

Prosecutors argued in a new court filing that a .22-caliber rifle with a scope and silencer and other evidence seized from the 1998 Ford should not be excluded from the proceedings involving Dominick Gullo, the man caught driving the van in Old Metairie after an automatic reader flagged its stolen license plate.

Authorities have said the May traffic stop may have prevented a violent crime from occurring, in part because the vehicle appeared to be furnished for an assassin, with custom “gun ports” built into its side panels and sawed-off dining room chairs mounted in its interior.

A grand jury indicted Gullo, 72, and Joseph F. Gagliano, an alleged passenger in the van, on charges of possessing an unregistered silencer, a violation of the National Firearms Act.

Gagliano, 55, a convicted racketeer with well-documented ties to organized crime, also was charged with being a felon in possession of a firearm in connection with the rifle, which had been stashed under a carpet inside the van.

Gullo’s defense attorney, Patrick Hand Jr., asked a federal judge recently to suppress any evidence collected from the van — including an 8-foot piece of cannon fuse, a wire capable of detonating an explosive device — under the “fruit of the poisonous tree” legal doctrine, a legal metaphor for evidence that is obtained illegally. Hand claimed the search violated Gullo’s Fourth Amendment rights because the authorities did not obtain a warrant until the next day.

Hand’s motion, if granted, would likely lead to the dismissal of the indictment against Gullo, even as authorities investigate whether the so-called sniper van had any intended targets.

Assistant U.S. Attorney William Quinlan, in a 10-page response to Hand’s motion, argued against the need for a hearing on the matter. Because Gullo failed to show proof of insurance or registration after being pulled over outside his East William David Parkway home, Quinlan wrote, state law required deputies to call in a tow truck and impound the vehicle.

That necessitated an inventory search, he added, to “protect any property within the van, insure against claims of theft or damage if an inventory wasn’t conducted, as well as guard against potential dangers by not inspecting what was being taken into police and/or the tow company’s custody.”

“Inventory searches are now a well-defined exception to the warrant requirement of the Fourth Amendment,” Quinlan said, citing a 1987 U.S. Supreme Court case that said authorities lawfully seized drugs from a backpack inside a vehicle after its driver was arrested for driving under the influence.

Prosecutors also pointed to a 5th U.S. Circuit Court of Appeals opinion that “impoundments by the police may be in furtherance of public safety or community caretaking functions.”

Hand has said his client had liability insurance that was not in his possession the night of the stop. Quinlan dismissed that claim, saying the insurance card later offered by Gullo was for another vehicle.

A hearing on Hand’s motion is scheduled for Thursday before U.S. District Judge Eldon Fallon.

Gullo was pulled over about 11 p.m. May 7 after passing a license plate-reading camera near Orpheum Avenue and Metairie Road. He claimed he had bought the van for $300 earlier that day from a woman who came into a coffee shop on Metairie Road seeking to sell the vehicle, and that he had not yet received the paperwork to complete the purchase.

While the authorities maintain Gagliano got out of the passenger side of the van after it was pulled over in front of Gullo’s home, the new court filings show Gagliano claims he was not inside the vehicle. “After the rifle and silencer were recovered from the van, Gagliano falsely stated that he was never in the van,” Quinlan wrote, “a statement Gullo concurred with.”

Gagliano served time in federal prison in the 1990s after pleading guilty to a racketeering conspiracy that defrauded Bally Gaming, a supplier of video poker machines, using companies that prosecutors portrayed as Mafia fronts. He is the son of Frank Gagliano Sr., who reputedly served as an underboss of the Marcello crime family in New Orleans before his 2006 death.

Gullo and Gagliano are set for trial Nov. 3 in U.S. District Court.

Follow Jim Mustian on Twitter, @JimMustian.