Sanghvi Art Jewellers on Agripada's B J Road, owned by Mansuklal Sanghvi, was robbed in broad daylight between 4.30 and 7.30 pm on Monday, when it was closed. But the heist on the usually busy road came to light only after 7.30 pm, when three of the shop's workers opened the shop.

The robber had opened the main door and the safe vault with duplicate keys before escaping with 5 kg of gold and other valuables worth Rs 33 lakh.But prima facie evidence suggested it could be the handiwork of some known person.

Police, who had earlier wondered how the heist on a busy road could have been carried out with such exactitude, then interrogated all of Sanghvi's family members. There were discrepancies in Sanghvi's nephew Amit's statements, a police officer informed.

Sustained interrogation revealed that Amit hadgained entry into the shop with duplicate keys after the shop's three employees had gone out for some work around 4.30 pm.

Amit had worked in the shop three years ago, and it was during this stint that he managed to duplicate the keys so that he could carry out the robbery in future. ``The robbery was planned in advance, and Amit seized the opportunity yesterday,'' an officer said.

Amit was arrested this afternoon, and the entire booty has been recovered from him, police confirmed. Amit told the police that he wanted a jewellery shop of his own, and he needed money for the purpose. Police are still questioning him to find out if he had any accomplice.

In another case, a chain snatcher and two receivers of stolen goods have been convicted to imprisonment by a magistrate at Girgaum Court today.

Mohammed Yakub Babu Azim Shah, a chain snatcher, who was named in 37 cases of chain snatching under the jurisdiction of Malabar Hill police station, has been convicted to rigorous imprisonment for 11 years. Tworeceivers of stolen goods, Ramesh Dhumal and Babulal Soni, have also been given three years in prison. The order was pronounced by a magistrate at Girgaum court today. Investigations were carried out by senior inspector D Bhonsale and police sub-inspector A Mane.