Lockheed Martin has fired CEO-elect Christopher E. Kubasik for having “a close personal relationship with a subordinate employee.” Marillyn A. Hewson, who was to succeed Kubasik as president and COO on Jan. 1, 2013, has been named to be the new CEO.

Lockheed asked for Kubasik’s resignation “effective immediately” after completing an ethics investigation sparked when an employee came forward at the end of October “with an expression of concern,” says Chairman and current CEO Robert Stevens.

Hewson has been appointed president and COO with immediate effect, and on Jan. 1 will become president and CEO, replacing Stevens, who will become executive chairman and remain with the company through 2013 to help with the leadership transition.

Describing himself as “disappointed and genuinely sad,” Stevens says a “robust succession plan” has allowed the company to react quickly. Lockheed “will not miss a beat” during the transition, he says. “It’s a temporary distraction,” Hewson adds.

Emphasizing that the company’s code of ethics applies to every employee, Stevens praises the “courageous action” of the person who came forward “with an allegation about our highest-level executive.”

The individual who came forward was not the employee with whom Kubasik had the relationship. “We conducted a thorough investigation, using an outside independent firm, which we felt was the appropriate to assure objectivity,” Stevens says.

When Kubasik and Hewson were promoted in April, the plan was for Lockheed to have both a CEO and COO. Under the new plan, Hewson as CEO will work directly with the executive vice presidents of the company’s five sectors.

“We will enter 2013 without a COO,” says Stevens, who adds that during his time with Lockheed Martin there have been periods when there was both a CEO and COO and others when there was just a COO.

Stevens say there is a specific plan in place for the phased transition of responsibilities during 2013. “We have a detailed process with discrete milestones to meet our commitments to customers…we will need to rephase that, and we have begun discussions.”