"The hard drive—which includes potentially revealing notes showing how Trump and his accountants arrived at their tax numbers—is believed to be locked in a high-security annex in lower Manhattan. A spokesman for the Manhattan District Attorney’s office declined to confirm the drive’s whereabouts, but people familiar with the office presume that it has been secured in a radio-frequency-isolation chamber in the Louis J. Lefkowitz State Office Building, on Centre Street. The chamber is protected by a double set of metal doors—the kind used in bank vaults—and its walls are lined with what looks like glimmering copper foil, to block remote attempts to tamper with digital evidence. It’s a modern equivalent of Tutankhamun’s tomb."
https://www.newyorker.com/magazine/2021/03/22/can-cyrus-vance-jr-nail-trump