New York real estate scion and accused murderer Robert Durst's bathroom muttering that he "killed them all" would likely be admissible evidence in a murder trial, legal experts said on Monday.

Durst, the subject of a six-part HBO documentary series called "The Jinx: The Life and Deaths of Robert Durst," was picked up by a filmmaker's microphone apparently acknowledging his crimes and admitting that he was "caught."

He was formally charged on Monday in the first-degree murder of a longtime friend, writer Susan Berman, in a 15-year-old cold case. Also on Monday, Durst agreed to be extradited to Los Angeles County from New Orleans.