Prosecutors will investigate officials from the unsuccessful Seoul mayoral campaign of Park Young-sun for allegedly violating election rules by recruiting an underage high school student to voice support for the candidate.

The Seoul Yangcheon Police Station said Tuesday that it has handed over the case to the Seoul Southern District Prosecutors’ Office recommending to indict 17-year-old student surnamed Kang and two officials from Park’s campaign office who were working for her Seoul mayoral run until April 7.

During Park’s campaign event on April 1 held in Yangcheon-gu, western Seoul, Kang went on stage to voice his support for Park’s bid for Seoul mayor as a candidate from the ruling Democratic Party of Korea. Rep. Jeon Yong-gi introduced Kang as a student who would vote for the first time, but Kang revealed during his speech that he was in fact not old enough to vote.

“I was actually born in 2004, so I am a second-year high school student,” Kang said during the speech. “I don’t have voting rights nor can join a political party but I stand here today to express my support for candidate Park.”

A campaign official soon after warned Kang to refrain from voicing his support, before cutting Kang off in the middle of his speech a few minutes later.

Investigators believe campaign officials and Kang violated the Public Official Election Act by having an underage student take part in the campaign. According to the law, those under 18, public servants and foreigners are not allowed to take part in local election campaigns.

Those who recruit or force them to take part in election campaigns can be sentenced up to three years in prison or a fine of up to 6 million won ($5,200).

Police started investigating the case on April 6 after receiving reports that Kang and campaign officials from Park’s camp violated this statute. Investigators accused these officials of failing to properly check Kang’s identification prior to having him take the stage.

Campaign officials from Park’s side then explained that verification was not properly conducted as speakers were recruited from using a Google Docs form. But the incident drew much criticism from the political circle until the election date.

Park’s campaign ended unsuccessful as she was defeated in all 25 of Seoul’s districts in competing against Oh Se-hoon from the main opposition People Power Party on April 7.