NEW ORLEANS -- Registering at a hotel under a false name and with phoney IDs cost real estate heir Robert Durst his right to privacy there, say federal prosecutors in New Orleans.

Durst, an estranged member of the family that is the co-developer of 1 World Trade Center in New York, is facing a murder trial in California in the death of his friend and onetime spokeswoman Susan Berman. He has waived extradition there.

But he's stuck in a Louisiana lockup awaiting a Jan. 11 trial on a federal charge that he illegally possessed a .38-calibre revolver after having a prior felony conviction.

The gun was found last March when Durst was detained in New Orleans. His attorneys will argue in federal court that the evidence seized in his New Orleans hotel room -- where he had registered under the name Everette Ward -- should be thrown out.

A hearing on the issue, originally set for Wednesday, is expected to be rescheduled for early October.

In a 65-page brief filed ahead of the hearing, prosecutors argue otherwise. The privacy issue leads off their arguments.

"One like Durst who so thoroughly immerses himself in a false identity, committing a separate offence in the process, should not later be heard to argue that society must recognize as legitimate his expectation of privacy in the hotel room," the attorneys wrote.

Durst's attorney, Dick DeGuerin, has declined public comment.

In filings, Durst's lawyers contend that the FBI and state police illegally searched his room at the J.W. Marriott hotel the evening of March 14, hours before getting a warrant and arresting him early March 15.

The arrest took place on the eve of the finale of a six-part HBO documentary called "The Jinx" about Durst, the disappearance of his first wife in 1982, Berman's death and the death and dismemberment of a neighbour in Galveston in 2001.

A self-defence plea won acquittal in the death of Morris Black, but Durst now is charged in Los Angeles with murder in the Berman case. Durst's lawyers say his arrest in New Orleans was timed to coincide with the conclusion of "The Jinx."