BOSTON (CBS) — “I care deeply about the democratic process and protecting its integrity,” said Facebook kingpin Mark Zuckerberg last year, as he performed damage control on the news that his service was used to spread false and divisive information during the 2016 campaign.

But Zuckerberg’s sincerity – along with the integrity of his company and the reams of user data it harvests – are now in question more sharply than ever after new revelations of lax controls over user data have damaged Facebook’s stock price and sent some customers heading for the exits.

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The latest wrinkle – a shady London-based research firm allegedly got its hands on the personal data of more than 50 million Facebook users and used the unauthorized harvest to help the Trump campaign. The company has denied any wrongdoing. Facebook asked the company, Cambridge Analytica, to delete the data, but never verified that they did so.

In a statement, Facebook says: “We are committed to vigorously enforcing our policies to protect people’s information and will take whatever steps are required to see that this happens.”

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But now a Facebook shareholder has filed a class-action suit accusing Facebook of lying about that, and politicians of both parties are hopping mad.

“If the industry can’t solve these kinds of problems by themselves, then we’ll have to solve them with legislation,” says Sen. Dianne Feinstein (D-California).

After several days of conspicuous silence, Zuckerberg finally released a long statement – on Facebook, of course – saying in part: “We will learn from this experience to secure our platform further and make our community safer for everyone going forward…. I know it takes longer to fix all these issues than we’d like, but I promise you we’ll work through this and build a better service over the long term.”

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But Zuckerberg, while admitting to mistakes, seemed to place the blame more on the data thieves than on his own lax security procedures. And with data harvesting at the core of Facebook’s business model, Zuckerberg mentor and early Facebook investor Roger McNamee tells CNN “this is a moment of truth. I can understand at the beginning that they did not appreciate how their strategy of growing at any cost might have negative repercussions. But the truth is, they have known for at least the year and there is no excuses.”