An internal NBC investigation found senior executives had no knowledge of Matt Lauer's sexual misconduct prior to his firing, the network said Wednesday.
The probe, based on interviews with 68 people, was launched after the famed "Today" show host was fired for "inappropriate sexual behavior in the workplace" on Nov. 29.
The long-awaited report said Lauer admitted on Nov. 28 to engaging in sexual activity with a woman. The woman had alerted NBC News managers the previous day.
Three additional current or former NBC employees came forward within the next two weeks accusing Lauer of subjecting them to inappropriate sexual behavior at work in 2000, 2001 and 2007.
"All four women who came forward confirmed that they did not tell their direct manager or anyone else in a position of authority about their sexual encounters with Lauer," the report says.
"Current and former members of NBC News and Today Show leadership, as well as News HR, stated that they had never received a complaint about inappropriate workplace behavior by Lauer, and we did not find any contrary evidence."
But the report didn't paint an entirely rosy picture of the network's handling of sexual misconduct allegations.
A woman who said she had a sexual encounter with Lauer in 2001 told the internal team that she informed her manager in or around 1996 about a troubling encounter with the NBC star.
The woman said Lauer "placed his hand on her thigh and made a sexually suggestive comment," the report says.
The manager asked about the woman's well-being. Then the pair agreed that the woman would not be assigned to any projects that would have required her to travel with Lauer.
The manager told the team conducting the probe that she did not recall reporting the incident to anyone, the report says.
Among the more disturbing allegations that emerged in the wake of Lauer's firing were accounts of the "Today" anchor using a secret button under his desk to lock his office door after inviting in women.
But the report pushes back against the idea that the device was installed for nefarious purposes.
"The button is a commonly available feature in executive offices in multiple NBCU facilities to provide an efficient way to close the door without getting up from the desk," it says. "It does not lock the door from the inside."
NBC News chairman Andrew Lack acknowledged that the company failed to create an environment that allowed employees to feel comfortable coming forward to report misconduct at its highest levels.
"I am immensely proud of NBC News, its history, and the work we do. But _ stepping back from the investigation _ that history also includes a time when people were not comfortable coming forward to voice complaints about repugnant behavior."
