lets go down a hypothetical path. im going to stress this is
totally hypothetical using Cowboy as an example.
So lets say Jones had something on Cerrone. Maybe he thinks Donald is supplying ped's out of his ranch etc..
USADA start an investigation but they also target test Donald hitting him twice in one week (as they actually did in July)
Donald tests positive in that second visit, but USADA dont make that public initially, instead, they contact Cerrone, say look, Jones has given us all the info, we know what you are doing. You have a choice. You can cooperate with us now, or we will go after you for a multi year ban.
Cerrone agrees to co-operate, so to keep that quiet in the short term they don't announce the potential violation (Which is standard USADA practise anyway, its UFC that make public the PV's)
Cerrone then starts blabbing in two directions.. one, where he gets his gear so that can start one line of enquiry.. second, he leaves Jacksons and starts blabbing about what he knows from his time there...
it really doesnt take much for these things to snowball.
Once one person blabs to save their skin, its amazing how many other people will think fuck it, im out for myself as well then, gonna do what I can to save my skin.
All the big cases, Balco, Armstrong, etc all started because one person blabbed and that started the ball rolling.