MENLO PARK, Calif. >>Twitter has handed over to Senate investigators the profile names, or “handles,” of 201 accounts linked to Russian attempts at influencing the 2016 presidential election. The company has stepped up its efforts to cooperate with investigators after it was criticized for not taking congressional probes seriously enough.

The handover occurred this week, according to a person familiar with the matter who was not authorized to speak publicly about it.

What remains unclear is whether posts associated with those accounts have been deleted from Twitter’s servers. Politico reported on Friday that the company had deleted the tweets in line with its privacy policy. Twitter had no comment on that report.

The company’s policy calls for removing tweets that a user deletes on their own. But that policy also states that some tweets can survive the process. For instance, retweets of deleted tweets will remain live if the retweeter added a comment. Twitter also can’t remove tweets that have been temporarily stored, or “cached,” by services such as Google or reposted on other sites.

Twitter might be able to recover some information about any deleted tweets, according to another person familiar with the situation who requested anonymity because of the sensitivity of the investigation. That person added that the company is working with investigators to find information that’s useful.

The account handles previously hadn’t been submitted in part due to legal privacy issues, the person said.

Twitter is set to appear Nov. 1 before the Senate intelligence committee at a public hearing. Both Facebook and Google have been invited to testify at the same hearing.

Twitter previously uncovered the accounts linked to Russia’s Internet Research Agency — a notorious “troll farm” known for pushing out pro-Russian positions via fake accounts — by using information provided by Facebook, which found 470 Russia-linked pages or accounts. After looking for patterns linking those accounts and pages to accounts on its service, Twitter said it had suspended 22 accounts that pushed divisive social or political issues during the 2016 campaign. It found another 179 related or linked accounts and took action against those that violated its spam rules.

The company enforces an anti-spam policy against bots and human users that exhibit unusual behavior. Such flags include having multiple accounts repeatedly retweet the same posts or having multiple accounts follow or block other users.

After Twitter’s initial closed-door briefing with the Senate committee late last month, Virginia Sen. Mark Warner — the top Democrat on the committee — called the company’s findings “frankly inadequate ” and “derivative” of Facebook’s work.