The Part I of article presents the current issues and latest trends of one of the public security policy one of priority – ensuring public security in combating crime. In article covers the main quantitative and qualitative indicators of the present-day crime in Lithuania and in the world; the key problems of crime prevention optimization and legal regulation and institutional problems of criminal process control are elucidated. This research focuses in particular on the importance of creating models for control and prevention of new crime acts. Also, the problems of prevention and control of some conditionally distinguished criminal processes – shadow economy, corruption, fight against human trafficking and violence in family environment – are scrutinized. As a result in this research is emphasised the importance of decentralisation in combating crime; the main guidelines of optimization and modernisation in this field are presented. The authors applied general scientific methods of studying objective reality, peculiar to legal sciences: systematic document analysis, metaanalysis, structural-functional analysis, teleological, comparative, critical approach, generalisation and prediction.