ONE of the two men behind the Chiltern Drive abduction and robbery was arrested on Friday afternoon in a police ambush near his home in Sengkang.

The 54-year-old man, a Singaporean, did not put up a struggle when confronted by police officers.

On Tuesday, two robbers made off with $50,000 after they confronted a woman in her 60s at knifepoint in her driveway and drove her BMW to a bank in Hougang Central where she withdrew the money and gave it to one of them.

They also held the woman's three-year-old grand-daughter and a Filippino maid captive in the locked car at a carpark.

By Wednesday, the police established the identities of the two robbers - who are friends - and where they live. They are not known to their victim.

Assistant Commissioner Ng Boon Gay, director of the Criminal Investigation Department, on Friday told a press conference how the police tracked down their man.

After police were alerted to the robbery, scores of officers went to the woman's plush bungalow off Braddell Road and the multi-storey carpark at Block 850A, Hougang Central, where her car was parked while she went to the bank to withdraw money.

They interviewed about 50 people and gathered clues and forensic evidence - including fingerprints - from the two locations.

About 30 police officers swung into action and laid an ambush on the older suspect on Friday afternoon.

He showed up in Sengkang at about 2pm and was caught as he was heading home.

Lead investigating officer, Assistant Superintendent Christopher Jacob, said that $350 cash was found on him.

'The officers went up to him and identified themselves and placed him under arrest. He did not put up any struggle,' he said.

AC Ng credited the success of the operation to the officers who had 'worked tirelessly round the clock for the past three days' and pledged to bring the other suspect, who is still at large, to justice.

'We know who he is, we know where he stays and we will be looking out for him,' he said.

The suspect, who is now on the run, is between 30 and 40 years old, slim and tanned, and about 1.7m tall. He was wearing a black jacket, dark trousers and a navy-blue baseball cap.

They interviewed about 50 people as they gathered clues and forensic evidence - including fingerprints - from the two locations.

Chairing his first press conference since he took over at the helm of CID, AC Ng said it was a combination of intelligence gather and hard work which led to the breakthrough.

'Through extensive forensics conducted at the scene of crime, officers from the CID and Ang Mo Kio police division were able to establish the identity of the subject,' he said.

With the identity, the police swung into action - with 30 officers mounting an ambush on the older suspect on Friday afternoon.

At 2 pm, he was caught when lead investigating officer, Assistant Superintendent Christopher Jacob, said that $350 cash were seized from his possession at the time of the arrest.

One of the robbers, a man in his 30s, had confronted the victim, a woman in her 60s, in the driveway of her bungalow in Chiltern Drive, off Braddell Road.

He then got into the rear seat of her BMW, along with her three-year-old granddaughter and Filipino maid, and ordered her to drive.

They picked up the older suspect along the way and the older man took over the wheel before they made their way to Hougang Central.