Gowdy, in remarks to reporters, did not identify the former CIA official, but said the deposition showed that Blumenthal "had no role at all in the authoring, drafting, vetting, accumulation of intelligence."
Gowdy suggested that the author of the memos could have had financial interests in Libya. "One of the folks providing [Clinton] the largest volume of information was simply and merely a conduit of someone who—it's still unclear—may very well have had business interest in Libya," he said.
"[Blumenthal] just forwarded it on from someone else. And if that someone else has a pecuniary interest in Libya, I would think that would be instructive," Gowdy said.
The comments from Gowdy and Blumenthal capped a day that featured partisan tensions over the Benghazi committee.
Democratic frustrations with the GOP-led Select Committee on Benghazi's probe were evident as several members said the deposition provides the starkest evidence yet that Republicans are using the investigation to wound Hillary Clinton politically.
Rep. Adam Smith said the deposition—which follows a subpoena last month—about Blumenthal's correspondence with Clinton had little to do with probing the 2012 Benghazi attacks.
"I think it is pretty clear at this point that this is a political investigation focused on Hillary," he said. Democratic Rep. Adam Schiff said: "If this witness weren't close to the Clintons, there's no way he'd be here today. This is all about GOP efforts to try to attack a likely Democratic nominee for president."
Gowdy defended the deposition against the Democratic allegations of political motives.
"I fail to see how we are playing politics by talking to someone who sent a large number of memos to the top diplomat we have during the relevant time period. If that is playing politics, then we just ought to shutter Congress and not do any more investigations," he said Tuesday afternoon.
Beyond the partisan charges and counter-charges, there was also apparent tension between two House Republicans.
The Hill reported that GOP Rep. Darrell Issa, who is not a member of the Benghazi panel, "tried to crash" the deposition, going briefly inside before being escorted out by Gowdy.
"The pair briefly exchanged hushed words in a nearby hallway before Issa stormed off, throwing an empty soda can into a nearby trash bin," The Hill reported. Issa previously conducted one of the numerous congressional probes of the Benghazi attacks when he was chairman of the House Oversight and Government Reform Committee.
On the eve of the deposition, the Benghazi panel's Republicans announced that Blumenthal provided the committee Friday with roughly 120 pages of his emails with Clinton that were not given to the committee by the State Department in February, when Libya-related emails were turned over. (Those were made public last month.)