A Starbucks store at the company's headquarters in Gangnam-gu, Seoul, is seen on Wednesday. (Yonhap) Police on Wednesday conducted a search and seizure at Starbucks Korea's headquarters as part of an investigation into the company's controversial "Tank Day" promotion.The Seoul Metropolitan Police Agency executed a search warrant at the company's headquarters in Gangnam-gu, Seoul, at around 8:50 a.m. Wednesday, roughly two months after launching the investigation following a complaint filed by a civic group.The warrant was issued in connection with a suspected insult offense, and investigators sought mobile phones, internal messaging records and planning documents. Police plan to analyze the evidence to determine whether the promotion was intentional and the extent of each employee's involvement.The controversy erupted on May 18, when Starbucks Korea launched a "Tank Day" promotion using phrases that critics argued mocked or distorted the historical significance of the May 18 Gwangju Democratic Uprising.Shinsegae Group dismissed then-Starbucks Korea CEO Son Jeong-hyun and another executive on the day the controversy emerged. Chairman Chung Yong-jin also issued a public apology, and the group launched an internal audit into the incident.The internal audit, however, was limited. Three of the five employees involved in planning the promotion reportedly refused to surrender their mobile phones. Internal messenger records from the campaign's initial planning stage could not be recovered because they had exceeded the company's data retention period.Police initially sought a search warrant on June 8, arguing that compulsory investigative measures were necessary to establish how the promotion was planned.Prosecutors, however, returned the warrant application, saying Starbucks Korea was cooperating with the investigation and that voluntary investigative measures should be pursued first.Police and prosecutors also reportedly disagreed over the applicable charges.Police initially sought the warrant based on allegations including violations of the Special Act on the May 18 Democratization Movement, insult and defamation. Prosecutors, however, concluded that only the insult allegation could be supported.Investigators have so far questioned company officials, including Shinsegae Group's head of audit, about how the promotion was planned, whether senior executives were involved and how the campaign was reported to Chairman Chung.