Alexander and Joyce testified that data collected through the PRISM and the Verizon data collection and surveillance programs has been used in at least 50 investigations, and that it was "critical" in at least half of them.
CNN's Peter Bergen's report questions and partially debunks those particular statements, seemingly confirming Senators Mark Udall's and Ron Wyden's earlier statement that as far as they can see, all of the useful information that the Verizon program has provided appears to have also been available through other collection methods that do not violate the privacy of law-abiding Americans.
Udall and Wyden, who are also members of the aforementioned committee, have called on President Obama to "probe the basis for these assertions".
Alexander also revealed that the NSA has only been using Section 215 of Patriot Act to obtain phone records and not credit card transactions (Kim Zetter pointed out that access to the latter are usually requested by other government agencies such as the FBI), that these phone records are kept for only 5 years and then destroyed, and that only 22 people at the NSA - including him and Litt - can authorize queries of this database.
He stated that due to what happened with Snowden, the NSA will be instituting a rule that will require two operators to sign of on downloading confidential data, and to change auditing and logging instructions so that one person can't effectively hide his or her tracks. He also disclosed that the NSA currently employs around a thousand sysadmins around the world, and that most of them are contract workers.
Finally, the government keeps insisting that these programs were kept secret so that terrorists wouldn't know about them, but John Mueller and Mark Stewart make some good points about potential real reasons for the secrecy.
The question now is can the committee trust the assurances of the officials that testified? Especially when one of them - Director of National Intelligence James Clapper - has admitted to not have told the truth in previous Senate enquiries.