The police have launched an investigation after one of the 17th-century swords went missing from the museum at the historic Danish Fort in the coastal town of Tharangambadi in Mayiladuthurai district.

The fort, which comes under the control of the State Department of Archaeology, is undergoing renovation work. The museum inside the fort houses several artefacts of archaeological and historical significance, including two iron swords dating back to the 17th century, each measuring about two feet in length.

According to officials, the museum was closed around 6 p.m. Wednesday. When staff opened the facility on Thursday morning, they found that one of the swords kept in a glass display case missing while the other remained in place. The CCTV cameras installed on the premises were not functioning at the time.

Dinesh Kumar, a junior-grade helper with the State Department of Archaeology, lodged a complaint with the Poraiyar police station. Based on the complaint, the police registered a case under Sections 331(4) and 305 of the Bharatiya Nyaya Sanhita (BNS) and initiated an inquiry.

The police officials said preliminary investigations are under way to determine how the artefact went missing from the secured gallery despite restricted access to the site. The functioning of surveillance systems and movement of personnel during the relevant period are being examined.