I disagree that anything happened "suddenly" in relation to the MM investigation and CB's alleged role in it.Perhaps LE have gone old school and beaten and tortured CB until he confessed?? We will never know.
Just seems all too odd to me that arguably one of the most famous cases in the world “suddenly” someone from the underworld has spoken up. Even weirder that this person provided evidence to support their tip.
In 2007 - CB was on police radar.
In 2008 - MC financed the only search of the dam based on an underworld tip off.
In 2013 - CB was again checked out. Perhaps as intelligence after MM's parents tv appearance.
In 2017 - I think investigators began to look at him in earnest.
So in reality, nothing was 'sudden', conversely it could be said " 'twas a long time coming!"