The Times also reported that prosecutors struggled to gather information that would tie members of the Intelligence Committee or their staff to the leaks, but Mr Barr declined to close the investigation after being sworn in in 2019. The case ended up being closed without charge.

A person close to Mr. Sessions said he was also unaware that the Justice Department had cited data from members of the House Intelligence Committee and their staff and families. At the time, investigators were trying to identify the source of leaks through the Russia investigation; Mr Sessions was excluded from most Russia-related matters after speaking with the Russian ambassador during the 2016 campaign.

Rod J. Rosenstein, Mr. Sessions’ deputy, who handled matters the Attorney General had withdrawn from, declined to comment.

In this case, members of the Intelligence Committee did not learn the full extent of the investigation until May, after a lockdown warrant against Apple expired and the company notified individuals whose data had been disclosed under the subpoenas.

But there were previous signs of activity as well. The FBI questioned Michael Bahar, a former member of the House Intelligence Committee, in the spring of 2020, according to current and former government officials.

A copy of the subpoena sent to Microsoft, verified by The Times, shows that the department was looking for records from April 2016 that may have linked the committee official to specific accounts, such as login, from where and when and other subscriber information, provided to Microsoft when the account was set up.

A Microsoft spokesman confirmed on Friday that it had received the summons but had also been exposed to a gag order for more than two years that prevented the company from informing legal counsel of the seizure.

Katie Benner contributed to the coverage.