Where did case No. JB100065 happen? Give the name of the district.
case No. JB100065 refers to case_number = 'JB100065'; name of the district refers to district_name
SELECT T1.district_name FROM District AS T1 INNER JOIN Crime AS T2 ON T1.district_no = T2.district_no WHERE T2.case_number = 'JB100065'