The ex-Amazon employee who allegedly hacked into the 5th largest credit card company in the US posted about it online, the FBI says.

• Former software engineer Paige A. Thompson hacked into Capital One systems and accessed information to more than 100 million credit card customers, according to prosecutors. Authorities say they tracked down the suspect after she allegedly talked about it online.
• Thompson was arrested by the FBI in Seattle and was charged with a single count of computer fraud and abuse.
• FBI agent Joel Martini laid out evidence, which was found online on Github, Slack, Meetup, and Twitter, in the criminal complaint.
• Visit Business Insider's homepage for more stories.

A software engineer in Seattle was behind the major Capital One data breach, which impacted over 100 million credit card customers in the US and Canada, prosecutors alleged in a criminal complaint.

Paige A. Thompson, a former Amazon employee, was arrested by the FBI in Seattle and appeared in court on Monday. She was charged with with a single count of computer fraud and abuse, and could face a sentence of up to five years in prison and a $250,000 fine.

The breach occurred on March 22 and 23, 2019. According to Capital One, the largest category of information that was compromised involved consumers and small businesses who applied for credit cards between 2005 and early 2019.

FBI agent Joel Martini laid out evidence, which was found online on Github, Slack, Meetup, and Twitter, in the criminal complaint.

• Read more: Capital One says it was hit with data breach, affecting tens of millions of credit card applications
• And: Amazon's cloud was at the heart of the big Capital One hack, even though it doesn't seem to be at fault

Kevin Mitnick, computer security consultant and convicted hacker, also posted on Twitter about the incident.

Scroll down to see the evidence that led to Thompson's arrest: