General Motors said two key finance executives are leaving the company as part of a sweeping restructuring of the corporate controller’s office.

The auto giant, whose accounting practices are currently being investigated by regulators, said controller Paul W. Schmidt will retire later this year at the age of 61 after 37 years with the company.

In addition, chief accounting officer Peter Bible has resigned “to pursue other career options,” effective June 1.

The company then plans to combine the positions of controller and chief accounting officer, and said it has hired Crist Associates to search for an external candidate.

GM spokeswoman Toni Simonetti told Bloomberg that Schmidt’s retirement had been planned “for some time” and that Bible’s departure was for “personal reasons.”

Simonetti also told the wire service that combining the finance jobs “is one way we can improve our internal controls and accounting.”

Bible, however, will remain as a consultant during the transition period, according to the company.

In addition, GM said it had retained financial advisory firm, AlixPartners, to help with a broad range of accounting and financial reporting matters. The firm, known for its turnaround expertise, will provide personnel to support the auto maker during is transition to a new controller and chief accounting officer, including assisting with assessments of the corporation’s internal, financial reporting and disclosure controls and implementing steps to improve them on an ongoing basis, according to GM.