Rep. David Cicilline speaks at a 2018 event. (Brookings Institution Photo / Paul Morigi / CC 2.0)

Amazon, Facebook, and Google finished their testimony at last week’s antitrust hearing, but the House Judiciary Committee isn’t letting them out of the hot seat.

Rep. David Cicilline, the chair of the subcommittee on antitrust, sent letters to the three tech giants Tuesday asking for more detailed and specific answers to questions raised during the hearing, according to copies obtained by GeekWire.

Four companies testified during last week’s hearing, but Apple did not receive a letter from Cicilline’s office. Amazon endured the most pointed questioning as members of Congress drilled into associate general counsel David Sutton on how the company uses data in the Amazon marketplace.

“Although I appreciate Amazon’s participation in the hearing, I was troubled by Mr. Sutton’s responses to questions from Members on the Subcommittee by offering either ancillary information or partial and selective responses,” Cicilline wrote in the letter to the company.

Both the letter and the hearing centered on the Amazon marketplace, where the company and third-party retailers sell goods. The subcommittee is trying to understand whether Amazon uses its trove of data to gain an unfair advantage over other players in the marketplace.

When the topic came up during the hearing, Sutton insisted that Amazon does not use an individual seller’s data to create products that directly compete with them. That left open the possibility that Amazon uses aggregated data to inform decisions like which products to develop.

Related: Lawmakers focus on Amazon during antitrust hearing, grilling company on marketplace practices

Cicilline’s letter asks, “Does Amazon use any of the data (including aggregate data on specific product categories) it collects on Marketplace transactions to inform its private label strategy?”

Other questions concern whether Amazon favors its products and the products of merchants who opt-in to the company’s fulfillment service above others. Cicilline also asked what percentage of the cloud computing and online retail markets Amazon captures.

GeekWire has contacted Amazon for comment on the letter.

Separately, the U.S. Justice Department on Tuesday announced that it has opened a review into “whether and how market-leading online platforms have achieved market power and are engaging in practices that have reduced competition, stifled innovation, or otherwise harmed consumers.”

The DOJ did not name the platforms it’s evaluating as part of the review.

“Without the discipline of meaningful market-based competition, digital platforms may act in ways that are not responsive to consumer demands,” said Assistant Attorney General Makan Delrahim of the Antitrust Division, in a statement. “The Department’s antitrust review will explore these important issues.”

Cicilline’s letter to Google, meanwhile, primarily focuses on the company’s dominance in search. He asked Facebook about its terms and conditions, and acquisition strategy.

The House Judiciary Committee is conducting an investigation into some of the biggest American tech companies to find out whether they use their market power anti-competitively. Amazon is also contending with an investigation by the European Union, where competition is regulated with broader strokes.

Though the House Judiciary inquiry sheds light on the issue, Congress does not have the authority to press charges against a company for violating antitrust law. That power is in regulators’ hands. The Department of Justice and Federal Trade Commission have sought clearance to launch an inquiry into the companies that testified during the hearing.

Cicilline’s letter to Amazon is included below.

Amazon Letter by GeekWire on Scribd

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