Zuckerberg withstood five hours of questioning by members of the House Energy and Commerce Committee in what was the second of two hearings set following news that political consulting firm Cambridge Analytica may have gained access to the personal data of up to 87 million Facebook users.

In contrast to the relatively gentle first Senate hearing on Tuesday, House lawmakers were more pointed with their questions on Wednesday, with several of them interrupting Zuckerberg when they felt he was giving evasive answers.

In an awkward exchange with Rep. Diana DeGette of Colorado, Zuckerberg said he did not know the details of two class-action lawsuits that Facebook had settled over privacy concerns related to data gathering techniques it has since changed. He also could not recall whether Facebook received a financial penalty related to a 2011 consent decree over privacy issues with the Federal Trade Commission (It didn’t, she reminded him).

“The reason I’m asking these questions, sir, is because we continue to have these abuses,” DeGette said. “At the same time, it doesn’t seem like future activities are prevented.”

Lawmakers also peppered Zuckerberg with questions about Facebook’s current data collection involving non-Facebook users. Rep. Ben Ray Luján of New Mexico brought up Facebook’s practice of collecting online information of non-registered users who, he pointed out, never have the opportunity to give their consent to it. Zuckerberg responded that this particular type of data collection is needed for security purposes, like preventing identity theft, which did not seem to satisfy Lujan’s concerns.

Rep. Debbie Dingell of Michigan highlighted Facebook’s other opaque data gathering techniques that typical Facebook users may be unaware of. These include Facebook tracking tools installed on third-party websites that are for serving targeted online ads and to let people more easily “like” articles without having to open the Facebook app.

When Dingell asked how many websites use these various Facebook tracking tools, Zuckerberg replied that his staff would get back to her, a common refrain the executive used throughout the two days of hearings.

New Jersey Rep. Frank Pallone asked whether Facebook would consider changing the default privacy settings of Facebook users “to minimize, to the greatest extent possible, the collection and use of users’ data.” Zuckerberg, however, responded that “this is a complex issue that deserves more than a one-word answer.”

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Lawmakers also appeared concerned about Facebook’s developer tools that let third-party software developers build apps on the social network. Academic Aleksandr Kogan used these tools to create a personality quiz app that siphoned data from Facebook users, which he then sold to Cambridge Analytica in violation of Facebook’s rules.

Despite Zuckerberg reiterating that Facebook later reduced the amount of data developers could collect, some lawmakers still expressed concern that once any data leaves Facebook’s systems, the company has no idea how it’s used.

Zuckerberg argued that the developer platform lets people “choose to sign into other apps and bring their data with them,” a feature “that’s something a lot of people want to be able to do.”

The repeated questioning over the nuances of Facebook’s data gathering techniques seemed to catch Zuckerberg off guard, and his lack of detailed answers appeared to frustrate some lawmakers who are concerned that another Cambridge Analytica scandal could happen under his watch.

Rep. Raul Ruiz of California explained that Facebook’s recent crises, despite the company operating under an FTC decree, may mean that the federal government should create a regulatory body that oversees how consumer data is collected and used. Zuckerberg said that the idea “deserves consideration,” but then added that “I think the details on this really matter.”