Generally crimes are classified , and as per serverity , crime is investigated by various dept. within Police Force.
Generally situation comes if chain snatching is very high or some one is troubling lot then that criminal matter is transferred to senior for investigation if his severity is high at same time if robbery of 50,000 takes places it may not be transfered to senior officer.
So your question is related to internal functioning of investigation dept. that is Police Dept.
I feel person who is in touch with Delhi Police establishment internal organization structure can only reply to this query.
In Mumbai there are various dept, EOW , Cyber crime, Women cell, anti terrorist cell , extrotion cell , etc.
So your query is too vaguge , if you tell the nature of crime may be we can guide you