CCM leaders are infamously known for their Kremlin-like tactics of liquidating people who appear to pose a threat on their 'interests'. It has done so to the late Horace Kolimba and same thing later happened to Chacha Wangwe and now they've vainly attempted to eliminate Mwakyembe, thanks God that Pollonium used is said to have already been expired.
Even so, why did they have to wait this long before considering an inquiry? It entirely sounds derisory and, to me, this investigation is a mere artifice just designed to expiate themselves from their spiteful ways.