In this week's indictment, Durst, 71, is accused of possessing a .38 caliber revolver, which authorities allegedly found in his hotel room last month.
He faces a maximum of 10 years in prison if found guilty of that charge, according to the indictment.
The charge is the latest in a litany of accusations.
A Louisiana judge ruled last month that Durst, who is charged with first-degree murder, will be held without bail at a facility near New Orleans.
Durst was featured this spring in "The Jinx," a HBO documentary about him. He's accused of killing his friend Susan Berman at her home in California in 2000. He also faces state weapons and drugs charges in New Orleans.
Last month, court documents claimed that
Durst had a loaded .38-caliber revolver, marijuana, his passport and birth certificate, a latex mask with salt-and-pepper hair attached and more than $40,000 cash.
He also had a UPS tracking number. The package was intercepted by the FBI, prosecutors said, and it contained clothing and more than $100,000 in cash.
Bigger fight awaits
But the bigger courtroom fight will probably unfold in Los Angeles, where the district attorney filed a first-degree murder charge against Durst
last month. He awaits extradition to Los Angeles to face that charge.
If convicted, he could face the death penalty.
Prosecutors accuse Durst of "lying in wait" and killing Berman, a crime writer and his longtime confidante, because she "was a witness to a crime."
Durst: I had nothing to do with it
Berman was shot in the head in her Beverly Hills home in December 2000, shortly before investigators were set to speak with her about the 1982 disappearance of Durst's first wife, Kathleen McCormack Durst.
Durst has long maintained that he had nothing to do with Berman's death or his wife's disappearance.
It's not the first time he has been accused of murder. He admitted killing and dismembering his neighbor at a 2003 trial, but he was acquitted after arguing that he acted in self-defense.
FBI agents have also asked local authorities to examine cold cases in locations near where Durst lived over the past five decades, a U.S. law enforcement official said. Unsolved cases in Vermont, upstate New York, the San Francisco Bay Area and Southern California are among those getting a new look, the official said.
Durst's attorney, Dick DeGuerin, said it's a sign that authorities are desperate.
Attorney: Durst has medical issues
DeGuerin has said Durst has serious medical conditions.
He is suffering from hydrocephalus, which required brain surgery a couple of years ago, DeGuerin said. Doctors implanted a stent on the right side of his head, the attorney said.
"At the same time he was in the hospital, he had an operation on his esophagus to remove cancer. So he's got some serious health issues. ... He's lost a lot of weight. He's not in good health," DeGuerin said.
DeGuerin also said that Durst is "mildly autistic" and has received treatment in the past from one of the country's leading experts in Asperger's syndrome and autism.