Shraddha Murder Case: Aftab`s polygraph test begins in FSL Rohini, know what all will happen?

Shraddha murder case accused Aftab's Polygraph test is being conducted in FSL Rohini. Today is the last round of Aftab's polygraph test in which Aftab will be asked the remaining questions. Knowwhy is Aftab's polygraph test being done again and again?