The mystery surrounding the sudden resignation of Flipkart co-founder and group chief executive officer Binny Bansal after investigation into an allegation of “serious personal misconduct” is gradually unraveling.

It pertains to an allegation made in 2016 by a former female employee of Flipkart. However, the charges could not be substantiated then, Economic Times reported.

At that time, Binny had just taken over as group CEO from co-founder Sachin Bansal, who had become executive chairman.

The complainant reportedly worked at Flipkart until 2012. In 2016, she started an event management company and again came into contact with Binny Bansal, the daily said.

In July this year, she approached Walmart Global after it had announced acquisition of a 77% stake in the company.

Walmart and Flipkart had roped in an international law firm that looked into the matter, even as Walmart closed the Flipkart deal by mid-August.

While investigating the issue, Walmart was reportedly upset that the matter had not been disclosed by Binny Bansal during acquisition negotiations. It had also examined payments allegedly made to the complainant.

Bansal denied the allegation of serious personal misconduct, but conceded that the investigation did bring to light lapses in judgment and lack of transparency in the way he responded to the situation.

Walmart acquired a 77% stake in Flipkart for US$16 billion after valuing the e-commerce firm at $21 billion. This was Walmart’s biggest acquisition and the biggest e-commerce deal globally.

Flipkart’s other co-founder and chairman Sachin Bansal left the company, selling his 5.5-6% stake for roughly $1 billion.