Police in Singapore are searching for a 41-year-old Indonesian domestic worker, who has been identified as a suspect in the double murder of an elderly couple on Wednesday afternoon.

The bodies of Chia Ngim Fong, 79, and his wife, Chin Sek Fah, 78, were found at 3:40pm in their five-room executive flat at Block 717, Bedok Reservoir Road, by their grandson, who was checking on them after they failed to answer a call from their son, Lianhe Zaobao reported.

Chia was found in the master bedroom while his wife was discovered in a bathroom. They had both been tied up with raffia fibre.

The police cited three knives found at the bottom of a rubbish chute at the building as evidence and categorized the case as murder. The police said the suspect could be a domestic worker, who had started working for the couple a month ago.

The Straits Times reported on Friday that the worker had likely boarded a ferry from Harbourfront Centre on Wednesday afternoon, having bought a ticket to either Batam or Tanjung Balai on Great Karimun in Indonesia.

The maid was hired through Sun Employment Agency, which is owned by the couple’s son and located at Bukit Timah Shopping Centre.

Chia was a manufacturer and retailer between 1964 and 1990. He and his wife had operated several retail stores in Singapore between 1990 and 2000, according to Accounting and Corporate Regulatory Authority records.