An International Crisis Group (ICG) report published on an African website and starts with:
Vigilante groups have been successful in providing local security. But subcontracting security functions to vigilante groups for counter-insurgency purposes is a dangerous option for fragile African states. African leaders should set clear objectives and mandates when enlisting vigilantes and invest in disarmament, demobilisation and reintegration programs.
The examples chosen are:
This report examines four cases in sub-Saharan Africa: the Kamajors, who fought in Sierra Leone's civil war (1991-2002); the Arrow Boys of Teso, who confronted the Lord's Resistance Army (LRA) in eastern Uganda (2003-2007); the Zande Arrow Boys, who battled the LRA and later rebelled against South Sudan's Dinka-led regime (2005-present); and the Civilian Joint Task Force, which has worked closely with the armed forces and police to counter Boko Haram in north-eastern Nigeria (2013-present).

Link to ICG:

Yes the report looks at Africa, might there not be parallels and lessons to note elsewhere?