Who carries out investigation for election-related criminal offenses?

Article261 Law No 8/2012 on Legislative Election

(1)   Investigators of the State Policeof the Republic of Indonesia shall deliver the results of the investigation tothe public prosecutor no later than 14 (fourteen) days after the reception ofthe report.

Source: http://aceproject.org/electoral-advice/archive/questions/replies/286046320/230159556/Unofficial-Translation-of-Law-8-2012-on.pdf