The NA62 experiment at CERN aims to measure extremely rare particle decays and, through comparison to precise calculations, potentially make discoveries of new fundamental physics processes including new particles and new forces of nature. To achieve this goal NA62 must carefully identify the types of particles (e.g. electrons, muons, and pions) present in the reactions with extremely high accuracy. The required rate of suppression of muons and electrons with respect to pions is ~1010 with efficiency of pion selection of 90%. A method to achieve this task based on two detector arrays - the Liquid Krypton (LKr) calorimeter and the Ring imaging Cherenkov detector (RICH). The required suppressions from LKr and RICH is approximately 105 and 102 respectively; additional suppression is available from other detector systems. The method will combine 2D image-like data from the LKr calorimeter with 1D image-like data from the muon chambers as well as high level event properties.