The later stories floating around today assert that the investigation of Lauer was going on for quite a while. Initially he denied everything, but more victims kept popping up. Eventually it sounds like he was done in by inside the office complex video cameras plus video from other reporting locations (public area in hotels, etc.) which confirmed some assertions he denied. In the end one of his victims with lawyer in tow demanded a meeting at the NBC network regarding his behavior (
http://www.foxnews.com/entertainment/2017/11/29/nbc-announces-today-show-co-host-matt-lauer-fired-due-to-inappropriate-sexual-behavior-at-work.html ) during the 2014 Sochi Olympics. This was enough to finally force the network to take action.
The payout on this for the victims is expected to easily surpass what FOX paid out.
However I am still waiting for more info to come out about this. Apparently a couple of media outlets were putting together stories on this.... and they fired him before they came out.