Nearly a month after Target revealed that its retail credit and debit card payment system had been breached, compromising the information of more than 100 million customers, the Chairs of the Senate Commerce Committee and the Senate Consumer Protection Subcommittee have written to the retailer asking it to explain just how a huge mistake like this could happen.

In a letter [PDF] sent on Jan. 10 (but only released today) from Senator Claire McCaskill of Missouri and West Virginia Senator Jay Rockefeller to Target President and CEO Gregg Steinhafel, the lawmakers write, “It has been three weeks since the data breach was discovered, and new information continues to come out… We expect that your security experts have had time to fully examine the cause and impact of the breach and will be able to provide the Committee with detailed information.”

To that end, the letter requests that Target’s information-security team “provide a briefing to Committee staff regarding your company’s investigation and latest findings on the circumstances that permitted unauthorized access to the financial information of so many Americans over the busiest shopping period of the year.”

Meanwhile, federal authorities, including the Secret Service, are continuing to investigate the breach and try to identify the hackers responsible.

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