McDonald's lost its top executive from the human resources department on Monday -- days after the company's top honcho was booted out for having an affair with a worker.

The burger giant based in Chicago said that Chief People Officer David Fairhurst's departure was unrelated to chief executive officer Steve Easterbrook's case. The British businessmen are close friends; after Easterbrook became a big boss, Fairhurst was promoted to his position in 2015.

"I thought the time has come for me to step on to my next professional opportunity," Fairhurst said on his LinkedIn profile.

McDonald's announced on Sunday that by having a consensual relationship with an employee, Easterbrook was fired for violating company policy.

Easterbrook acknowledged the affair in a letter to staff and said: "it was a mistake."

"I agree with the board that it's time for me to move forward, given the company's principles," Easterbrook said in the letter.

McDonald's would not give details of the employee involved with Easterbrook. Easterbrook's attorney refused to answer questions.

In a filing before the Securities and Exchange Commission, McDonald's said that as part of his severance agreement, Easterbrook will receive six months' pay but will forfeit millions of uninvested stock options.

The compensation for Easterbrook for 2018 amounted to $15.9 million. That included a salary of $1.3 million, and the rest included stock options and incentives.

Easterbrook will be eligible for a prorated incentive payment for the 2019 fiscal year pursuant to its severance agreement. He can also exercise stock options that, within three years, have vested or will vest.

At the end of 2018, Easterbrook had $21.8 million worth of uninvested options. Easterbrook also has a two-year prohibition on working for a competitor.

The board appointed Chris Kempczinski as the new chairman and top executive of the company. Recently, Kempczinski served as president of a U.S. subsidiary of McDonald's.

McDonald's Corp. announced Monday that the base salary for Kempczinski would be $1.25 million, and 58 percent higher than his payment for 2018.

Analysts said Monday that Kempczinski - who joined McDonald's in 2015 - is likely to follow Easterbrook's path, including redesigning U.S. stores to make them more digitally knowledgeable and testing drive-thrus' voice-based technology.

"We believe that these initiatives will remain largely unchanged and that the legacy of Mr. Kempczinski will depend on his ability to generate traffic growth in the U.S., which none of his two predecessors have been able to achieve," said BTIG Managing Director Peter Saleh in a note to investors.

Shares of the company were down 3 percent to $187.60 during after-hours trading.