What is the difference between people who are viewed as “not guilty”, “factually

What is the difference between people who are viewed as “not guilty”, “factually guilty”, and “legally guilty”? Should the primary focus of the criminal justice system be to apprehend and sanction as many factually guilty people as possible? Or should it be to make decisions according to legal principles and requirements, which may result in releasing a number of factually guilty people? Which rule is the most accustomed practice in Ethiopian criminal justice system? Thus, explore different literatures, international instruments and domestic laws to justify your arguments.