From the National Archives and Records Administration (NARA):
The National Archives released, in full, the formerly secret grand jury testimony of William Danziger, the sole remaining sealed grand jury witness transcript from the trial of Ethel and Julius Rosenberg.
This additional transcript is now available in response to a court order (dated January 31, 2017) directing its release because the witness is deceased. In 2008, the court ordered the release of transcripts for the 43 Rosenberg grand jury witnesses who were deceased or did not object, but withheld the transcripts of David Greenglass, Max Elitcher, and William Danziger due to their objections.The court indicated that these transcripts could be released upon their deaths. The transcripts of the Greenglass and Elitcher testimony were released pursuant to a court order in 2015, but it was not known at that time whether Danziger was still alive or continued to object to the release of his transcript. The court was informed in late 2016 that Danziger died in 2012, and that he is survived by two children who asked that their father’s testimony be unsealed.
The transcripts are available on the National Archives web site.
Background About Previously Released Grand Jury Transcripts