The heist was discovered when shop owner Sisir Majumder visited his workplace on Sunday morning.

There were, however, no signs of forced entry but the almirahs in the shop, including the shutter, had been unlocked.

No arrest has been made as yet but preliminary investigation hint at an insider’s hand, police said.

“It is strange that the robbers entered after opening the locks. They must have had the keys. We will approach fingerprint experts. Our investigation is on,” said Praveen Kumar, Superintendent of Police, South 24 Parganas.

According to police, like every other day the shop was shut on Saturday around 9 pm. When the staff and Majumder came to work at around 9 am, and discovered the unlocked shop.

When they stepped inside, they discovered the shop was ransacked, and gold and silver jewellery worth Rs 7 lakh was missing.

A formal complaint was lodged by Majumder. Police later interrogated the staff.