Ind. Code § 33-39-2-2

Sec. 2. A prosecuting attorney or deputy prosecuting attorney may not perform a duty set forth in section 1 of this chapter until the prosecuting attorney or deputy prosecuting attorney obtains a seal that stamps upon paper a distinct impression:

(1) in words or letters sufficiently indicating the official character of the prosecuting attorney or deputy prosecuting attorney; and

(2) that may include any other device chosen by the prosecuting attorney or deputy prosecuting attorney.

All acts not attested by a seal are void.