Who prosecutes election-related criminal offences?

India
CHAPTER IXA. OF OFFENCES RELATING TO ELECTIONS.
171A.For the purposes of this Chapter-
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1) Whoever—
(i) gives a gratification to any personwith the object of inducing him or any other person to exercise any electoralright or of rewarding any person for having exercised any such right; or
(ii) accepts either for himself or forany other person any gratification as a reward for
exercising any such right or for inducing orattempting to induce any other person to exercise any such right, commits theoffence of bribery: Provided that a declaration of public policy or a promiseof public action shall not be an offence under this section.
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Sections 171C/171F of the Indian Penal Code
Undue influence at election –
. (1) Whoever voluntarily interferes of attemptsto interfere with the free exercise of any electoral right commits the offenceof undue influence a an election.
(2) Without prejudice to the generality of theprovisions of sub-section(1), whoever-
(a) threatens any candidate or voter, orany person in whom a candidate or voter is interested, with injury of any kind,or
(b) induces or attempts to induce acandidate or voter to believe that he or any person in whom he is interestedwill become or will be rendered an object of Divine displeasure or of spiritualpleasure, shall be deemed to interfere with the free exercise of the electoralright of such candidate or voter, within the meaning of subsection
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Source:
http://bombayhighcourt.nic.in/libweb/oldlegislation/ipc1860/Chapter%209.pdf