The executive at the heart of Target's major credit-card security breach is resigning, amid an overhaul of the retailer's digital security.

Beth Jacob resigned effective today as chief information officer, the company said in a note to its employees. Target said it will look outside the company for her replacement.

In addition to replacing Jacob, Target said it plans to hire a chief compliance officer – a role the company didn't previously have.

Related: Preventing Another Target Hack

“While we are still in the process of an ongoing investigation, we recognize that the information security environment is evolving rapidly," Target CEO Gregg Steinhafel said in his letter. "To ensure that Target is well positioned following the data breach we suffered last year,we are undertaking an overhaul of our information security and compliance structure and practices."

Target faced a sophisticated hack that exposed data from 40 million credit cards and 70 million customers. So far, Target has racked up more than $60 million in charges as a result of the breach, which was one of the largest for a retailer in history.

Related: Target Accelerating Program to Detect Credit-Card Fraud