Among all the crimes that had happened in Central Chicago, how many of them were cases of domestic violence?
Central Chicago refers to district_name = 'Central'; case of domestic violence refers to domestic = 'TRUE'
SELECT COUNT(*) FROM Crime AS T1 INNER JOIN District AS T2 ON T1.district_no = T2.district_no WHERE T2.district_name = 'Central' AND T1.domestic = 'TRUE'