Controversial Alphabet chief legal officer David Drummond has announced he will be following the Google co-founders out the door, retiring from the company amid an ongoing investigation into his conduct.

Drummond has been involved with Google since its inception, helping to incorporate the company in 1998. He has remained a top executive at Google and its parent company Alphabet since.

His resignation from the company comes just a month after Google co-founders Larry Page and Sergey Brin stepped down as CEO and president of Alphabet.

Google and Alphabet employees were told of Drummond’s decision to retire via an all-staff memo.

“With Larry and Sergey now leaving their executive roles at Alphabet, the company is entering an exciting new phase and I believe that it’s also the right time for me to make way for the next generation of leaders,” Drummond’s memo said.

“As a result, after careful consideration, I have decided to retire at the end of this month.”

Drummond’s retirement comes amid an ongoing investigation into how Google executives have handled misconduct claims at the tech giant, and reportedly also into Drummond’s own relationships with employees.

In a Medium post last year, former Google employee Jennifer Blakely detailed her relationship with Drummond, who was married at the time, beginning in 2004. The relationship was in violation of Google’s new policy on international workplace relationships.

Blakely and Drummond had a baby in 2007, and in the blog post, Blakely accused Drummond of leaving her and her son for another Google employee.

In response to the post, Drummond acknowledged the relationship and the “difficult break-up 10 years ago”.

“Other than Jennifer, I never started a relationship with anyone else who was working at Google or Alphabet,” Drummond said. “Any suggestion otherwise is simply untrue.”

Just days after issuing that statement last year, Drummond married another Google employee who he had been dating.

After more than 20,000 Google employees raised concerns with how the company had handled reports of sexual harassment and inappropriate workplace relationships, an investigation was opened into the matter, with an independent subcommittee created and an independent law firm engaged.

Drummond’s handling of misconduct reports and his own relationships are reported to be a subject of the investigation.

Drummond was also facing a lawsuit that had been filed by Alphabet shareholders accusing the company’s leadership of covering up sexual harassment scandals.

Google has denied that Drummond will be receiving an exit package. Since November, he has sold more than $US200 million in Google stock.

Google Ventures founder Bill Maris, who reported to Drummond until he quit in 2016, said the outgoing legal boss was the reason he left the company.

“I simply could not work with him any longer,” Maris told Axios. “It’s that simple. We have very, very different ideas about how to treat people, and this was a long time coming.”

Drummond’s departure continues a major changing of the guard at Google after its co-founders stepped away.

Page and Brin will continue to have input in the company’s overall direction and maintain 56 per cent of the stockholder voting power.

“We are deeply committed to Google and Alphabet for the long term, and will remain actively involved as board members, shareholders and co-founders,” they said.

“We are deeply humbled to have seen a small research project develop into a source of knowledge and empowerment for billions.”