Masterminding the daring daylight heist, M. Jegatheesh, 28, targeted a jewellery shop in Ang Mo Kio as the owners were elderly and he thought it did not have an alarm system.
The private-hire driver roped in two others including a getaway driver and tried to avoid detection by using carparks without electronic gantries.
He also wore a disguise.
The trio made away with jewellery worth $119,000 but were arrested within 36 hours.
Yesterday, Jegatheesh was jailed for three years and three months and given six strokes of the cane after pleading guilty, midway through a trial, to plotting the robbery.
Two other charges were taken into consideration.
One accomplice, Sharavindran Suppiah, 32, admitted to dishonestly receiving stolen property. He faces 31 other charges for various offences and will be sentenced today.
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The getaway driver, Veeramani Subran Das, 37, was earlier jailed for three years and given six strokes of the cane.
Jegatheesh told the two men on Aug 13 last year that he intended to rob Hock Cheong Jade and Jewellery at Block 574 Ang Mo Kio Avenue 10.
He told Veeramani, also a private-hire driver then, that he would pay him to be the getaway driver and to ferry the loot to Sharavindran, who was supposed to help sell it. The next day, Jegatheesh met Veeramani at a carpark near Block 521 Ang Mo Kio Avenue 5 at 2.40pm.
He put on a long-sleeved blue shirt and a hoodie, gloves, and a helmet, and told Veeramani to drive to another carpark nearby and wait for him there.
Entering the store at about 4pm, Jegatheesh tried to pull down the shutter at its entrance but gave up as it got stuck.
He shouted at shop owners Ling Hew Kwong, 70, and his brother Leng Yew Weng, 75, and jumped over the counter.
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Unlocking the display cabinets, he swept valuables, including gold necklaces, bracelets, and pendants, into a duffle bag.
The shop owners did not confront him as they feared getting hurt, but they were able to press a hidden alarm button to notify an external security company.
Mr Ling's shouts for help also alerted two people nearby, and one of them called the police.
Jegatheesh and Veeramani escaped and the latter met with Sharavindran later that day.
Unable to sell the loot, Sharavindran hid the items inside the cistern of a toilet bowl in a flat at an abandoned block in Dakota Crescent. The police recovered all the stolen jewellery.
This article was first published in The New Paper. Permission required for reproduction.