Under Taiwan’s election laws, bribing people to sign or not sign for a potential candidate is punishable by a maximum seven-year jail term, in addition to a fine of up to NT$10 million.
The case is among around a dozen investigations launched over Gou’s signature campaign, local media reported.
Prosecutors in the capital Taipei said on Wednesday that they were investigating two bribery cases connected to Gou’s signature campaign.
A total of 13 suspects were questioned on Tuesday and released on bail, according to Taipei district prosecutors’ office, without elaborating on the allegations.
Gou’s campaign office announced on Thursday that over 1.03 million signatures were filed.
In China, Foxconn is under tax and land probes in several provinces, Beijing’s state-run Global Times reported last month.
The investigations come as self-ruled Taiwan – which China claims as its territory and has vowed to seize one day – prepares to hold presidential elections on Jan 13.
Officials from Taiwan’s ruling Democratic Progressive Party, including its presidential candidate and Vice-President Lai Ching-te, have defended Foxconn and accused Beijing of trying to interfere in its elections.