(CNN)Robert Durst appeared to be prepared for life on the lam when FBI agents arrested him in New Orleans. The millionaire heir, according to court documents, had more than $40,000 in cash with him -- and a neck-to-head latex mask to alter his appearance. The new details about Durst, who's been charged with first-degree murder, emerged Wednesday in court documents supporting a search warrant for his Houston home. It's the latest twist in a whirlwind week for Durst, the subject of HBO's true-crime documentary "The Jinx." He's gone from a man battling suspicions that he killed three people to a frail 71-year-old on suicide watch. Durst, whose real estate developer family is among New York's wealthiest, has a net worth of about $100 million and had been withdrawing large sums of money from various bank accounts, including daily withdrawals of $9,000 over 35 days since October, the court documents said. He's being held on drug and weapons charges in Louisiana as he awaits extradition to Los Angeles to face charges in the 2000 killing of his close friend. It's not the first time he's been accused of murder. He admitted to killing and dismembering his neighbor in a 2003 trial, but he was acquitted after arguing he acted in self-defense. And while he's never been charged in his first wife's 1982 disappearance, her family members say they believe she's dead and that he's the one to blame. FBI agents are also investigating whether Durst could be connected to other unsolved murder cases. The agency is putting out a call to 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. Durst's apparent plans to flee began to unravel on Saturday, after an FBI agent approached him from behind at a New Orleans hotel and said, "Mr. Durst?" Although Durst had checked into the hotel under the name "Everette Ward" and carried a Texas ID card with that name, he turned around when the agent called him by name, according to court documents. In his hotel room, agents found more than $40,000 in cash, mostly in $100 bills packed into small envelopes, a loaded revolver, the rubber mask that covers the head and neck, his actual birth certificate and passport, and marijuana. On Tuesday, authorities made it clear they weren't done looking into Durst, even though he's behind bars. At the Houston condominium building where Durst owns three units and lived for many years, authorities seized compact discs, bank statements, handwritten notes, credit cards and checks, stationery, a cell phone, boxes of court documents, photos and a trash bag of court transcripts. They also left with copies of books that detail the disappearance of his first wife and his legal troubles: "Without a Trace" and paperback and hardcover copies of "A Deadly Secret." Journalist Matt Birkbeck, who wrote "A Deadly Secret," said he'd heard Durst read his book, but didn't realize he still had two copies. "When I first heard that, I was somewhat shocked," Birkbeck told CNN, "and a little disturbed." The Los Angeles County district attorney filed a first-degree murder charge against Durst on Monday. If convicted, he could face the death penalty. Prosecutors accuse Durst of "lying in wait" and killing Susan Berman, a crime writer and his longtime confidante, because she "was a witness to a crime." Berman was shot in the head in her Beverly Hills, California, home in December 2000, shortly before investigators were set to speak with her about the disappearance of Durst's first wife, Kathleen McCormack Durst, in 1982. Durst has long maintained he had nothing to do with Berman's death or his wife's disappearance. He's confined to a Louisiana prison's mental health unit after being deemed a danger to himself. On Tuesday, an appeals court granted a request from the Orleans Parish Sheriff's Office to move Durst to the Elayn Hunt Correctional Center's mental health unit in St. Gabriel, about an hour's drive from New Orleans. Lawyers for the sheriff's office argued that the jail where Durst was being held until Tuesday night can't accommodate inmates with acute mental health conditions. The appeals court agreed. Durst's lawyer Dick DeGuerin said he "did not believe" his client was mentally ill, and that he should remain in Orleans Parish to give the legal team better access to him before a evidentiary hearing scheduled for Monday. DeGuerin has said it's no coincidence authorities arrested Durst the day before the HBO documentary's final episode aired. He said he wasn't surprised about the search of his Texas condo, either. "They're acting like a bunch of Keystone Kops, particularly after being embarrassed by the TV program," he said. "And I'll be even more surprised if they find anything of any evidentiary value whatsoever." Authorities have been mum about what evidence led them to arrest Durst on Saturday, the day before the finale of "The Jinx" aired. Court documents reveal some details about their case against him. Four forensic experts concluded a letter sent to police telling them to search for a cadaver in Berman's home was likely written by Durst. For viewers of the HBO documentary, that might not come as a surprise. In "The Jinx," Berman's stepson stumbles upon a signed letter from Durst to Berman's home in Beverly Hills. The handwriting looks similar to the "cadaver" letter that tipped off police to the killing, and both letters misspell the word as "Beverley." In the documentary, Durst denies he has anything to do with writing the "cadaver" letter, and that he has anything to do with Berman's death. Court documents mention another anonymous letter, sent from New York in January 2001, to a Los Angeles police detective. It was titled "Possible motive for Susan Berman murder" and stated that Berman suspected Durst of being involved in his wife's disappearance. It also said Durst planned to visit Berman around the time of her death. In a 2003 murder trial, Durst admitted he'd killed neighbor Morris Black in Galveston, Texas, and chopped up the body. He was acquitted after his attorneys argued he had acted in self-defense, though he later served nine months in prison on felony weapons charges stemming from that case. DeGuerin told reporters Monday that his client didn't kill Berman. "He's ready to end all the rumor and speculation and have a trial," DeGuerin said. It's not clear when a trial would take place. Durst waived his right to fight extradition to Los Angeles, but because prosecutors in New Orleans are pursuing charges against him, he remains jailed there. Investigators believe he planned to travel from New Orleans to Cuba, a law enforcement official told CNN. Investigators found a .38-caliber Smith & Wesson revolver and about 147 grams (5.2 ounces) of marijuana in Durst's hotel room in New Orleans, according to court documents. He was booked on charges of possession of a firearm by a convicted felon and possession of a firearm in the presence of a controlled dangerous substance. Court documents filed Tuesday say Durst will receive medications while imprisoned, "including but not limited to hydrocodone as needed for pain." CNN's Evan Perez, Chandler Friedman, Jeremy Grisham, Dave Alsup, Holly Yan, Chris Welch, Shimon Prokupecz and Kevin Conlon contributed to this report.
The FBI is looking into unsolved murder cases in areas where Robert Durst has lived . He's charged with first-degree murder in the slaying of his longtime friend in 2000 . Court documents reveal he had more than $40,000 in cash and a mask when agents arrested him .