A day after he was indicted by an Orleans Parish grand jury, Robert Durst, the New York real estate heir and accused killer, pleaded not guilty Thursday to state firearms and drug charges.

Durst, a multimillionaire charged in Los Angeles with fatally shooting Susan Berman, his onetime confidante, faces counts in New Orleans of illegal carrying of a weapon with a controlled dangerous substance and possession of a firearm by a convicted felon — charges stemming from the loaded handgun and marijuana authorities found in his Canal Street hotel room last month.

Durst, who turns 72 next week, appeared frail and lethargic at a brief court hearing Thursday, struggling to rise from a chair and to hear Criminal District Court Judge Franz Zibilich.

“I’m not guilty, your honor,” Durst said after conferring with one of his lawyers, a team of defense attorneys that seems to grow larger at each proceeding.

The local prosecution has postponed indefinitely Durst’s return to Los Angeles, where prosecutors recently charged him in a 2000 murder that became a national sensation after an HBO documentary series raised new suspicions of Durst’s involvement in Berman’s death.

The series, “The Jinx: The Life and Deaths of Robert Durst,” ended with dramatic off-camera remarks from Durst that some interpreted as a confession to multiple killings. The series also examined Durst’s possible connection to the 1982 disappearance of his wife, who is presumed to be dead.

Durst’s defense attorneys contend the murder case in California relies too heavily on the documentary and is devoid of new evidence.

The Louisiana charges could yield a lengthy prison term for Durst before he sees the inside of a California courtroom, particularly if prosecutors seek to have him sentenced as a habitual offender.

In a new wrinkle, federal authorities this week brought their own case against Durst, as the FBI filed a criminal complaint accusing him of possession of a firearm as a felon, a charge that carries a sentence of up to 10 years behind bars.

“This makes things a lot worse for Durst,” said David Weinstein, a former federal prosecutor in Miami who has followed the case closely. “He’s going to do some (prison) time, and now he’s not going anywhere until he finishes his federal case.”

The federal firearms case, for which Durst is expected to appear in court next week, appears to be stronger than the state case, Weinstein said, in part, because it is based on a 2004 federal conviction Durst received for jumping bail and carrying a weapon across state lines as he attempted to flee a murder prosecution in Texas, a killing for which he ultimately was acquitted.

Durst’s attorneys, seeking to have the state arrest warrant quashed, have claimed those prior felonies could not be applied to the charge of being a felon in possession of a firearm under Louisiana law.

That argument, Weinstein said, will not hold water in the federal case, where the applicability of Durst’s prior conviction is unequivocal.

Durst’s attorneys also have claimed authorities failed to secure a warrant before conducting an improper “inventory” of his room at the JW Marriott Hotel on Canal Street — where Durst was staying under an alias — that revealed the handgun and marijuana, along with a list of items suggesting Durst was prepared for a life on the lam.

Among his possessions were a latex mask with salt-and-pepper hair and tens of thousands of dollars in cash. Invoking the HBO documentary, the FBI’s criminal complaint says Durst “had allegedly stated his last interview would be conducted in Cuba or Havana.”

While Weinstein predicted the state charges would take a back seat to the federal firearms case, Craig Mordock, a former New Orleans prosecutor, noted that two of District Attorney Leon Cannizzaro’s top prosecutors are handling the state proceedings against Durst: his daughter, Laura Rodrigue, and Bobby Freeman, a senior prosecutor.

Even though Durst isn’t fighting extradition, Mordock said, the soonest he can expect to return to California is early 2016.

The aggressive posture taken by state and federal prosecutors in New Orleans, Mordock added, could be a reflection of the weaknesses in the California case.

“It’s the Al Capone theory,” he said. “Get him on something.”

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