YOU SAID:

if the man did do the crime, then the cops must have a chase

INTO JAPANESE

男が犯罪をした場合、警官は追いかけなければなりません

BACK INTO ENGLISH

If a man commits a crime, the policeman must follow

INTO JAPANESE

男が犯罪を犯した場合、警官は従わなければなりません

BACK INTO ENGLISH

If a man commits a crime, the policeman must follow