SINGAPORE - A few days after the first group of Jemaah Islamiah (JI) members in Singapore were nabbed on Sunday, Dec 9, 2001, several members who heard of the arrests met at a HDB void deck. They then headed to a fellow JI member's house to discuss their options.

The mood was one of panic and anger, former detainee Johan (not his real name) recalled. They were told to destroy all incriminating evidence so the authorities would not get their hands on them.

Mas Selamat Kastari, the leader of the Singapore JI, advised them to leave Singapore. He also suggested they hijack a plane and crash it into the Changi Airport control tower.

A few days later, Johan drove to Marsiling, abandoned his van, and walked across the Causeway. Malaysian JI members took him and other Singapore JI members who also made their way across to a safe house in Johor.

In all, about 20 JI members managed to leave the country.

But two of those at the meeting who stayed behind were apprehended by the Internal Security Department (ISD) on Dec 15 and 16.

On Dec 28, they told investigators about the plan to target Changi Airport. That same day, officers arranged to meet their foreign liaison partners and sought their assistance to pass the information to the US Federal Aviation Authority (FAA).

A day later, the FAA issued an alert on Mas Selamat's hijack plans.

The move proved to be critical in averting a catastrophic attack. Mas Selamat was forced to abort his plan after discovering he was named in Thai newspapers as a wanted terrorist.

It also illustrated the key role foreign partnerships played in hobbling the regional JI network and pursuing the fugitives who had fled the security dragnet.

Weeks before the Sept 11, 2001, Al-Qaeda attack on America, Malaysian police arrested 10 men who they found were members of Kumpulan Mujahidin Malaysia, or KMM, for involvement in robbery, murder and other crimes.

Not much was known about them, except that many had trained and fought in Afghanistan in the mid-1990s, and had ambitions of establishing an Islamic state in South-east Asia.

It was only after the arrests of the JI members in Singapore later that year that a link was made between the KMM and JI.

Former Federal Bureau of Investigation special agent Frank Pellegrino, who was in this region frequently and investigating terrorism, recalled receiving information from the ISD on the arrests.

"We cross-referenced the names with the help of our friends in Singapore and Malaysia, and it was clear there were many mutual associates and members of KMM and Jemaah Islamiah," he said in an interview.

There was more. Two of the Sept 11 hijackers of the plane that crashed into the Pentagon had visited Malaysia in 2000 and stayed with JI operative Yazid Sufaat.

Yazid and Malaysian JI member Faiz Bafana - who was in the Singapore cell and nabbed by the ISD - also assisted 9/11 conspirator Zacarias Moussaoui when he visited Malaysia in late 2000.

Mr Pellegrino was granted access to interview Faiz, who later testified against Moussaoui.

Faiz also provided leads on Al-Qaeda operative Mohammed Mansour Jabarah, or Sammy, who was involved in a plot to bomb the US embassy in Singapore, along with other Western embassies. He was arrested in Oman in early 2002, and is now serving a life sentence in the US.

Another lead provided by the JI member was on Al-Qaeda bomb-maker Fathur Rohman Al-Ghozi, known as Mike.

A senior intelligence official in the Philippine National Police who is involved in counter-terrorism efforts said this enabled them to arrest Mike in Manila in January 2002.

Intelligence that was provided on JI also "aided in foreign partners' arrests of terror suspects and foiling of attack plots within their countries", he said.

Mike's arrest, the official noted, led to the discovery of 1.2 tonnes of TNT - enough for five vehicle-borne improvised explosive devices - along with 300 pieces of detonators and six rolls of detonating cords, in a storage facility he had established in General Santos City in southern Mindanao that month.

The Philippine official said these explosives were part of a total of six tonnes of TNT Mike had ordered in the Philippines for the truck-bomb attack plots in Singapore against the Western targets. They were to be transported to Singapore via Indonesia and Malaysia.

Mike, the official added, had discussed with other JI members how to transport and store these explosives procured in the Philippines, and to source warehouses in Singapore, where the rigging of the bombs to the trucks could be done without detection.

"Had the Singapore JI network not been uncovered by ISD, which led to Mike's subsequent arrest, there was a very real possibility that the attack could have taken place and the consequences would have been catastrophic," the official said.

Even when the detainees did not have knowledge of plots being formed, their ability to identify those involved - such as Amrozi, a ringleader of the October 2002 Bali bombings that killed 202 people - proved helpful to investigators in Indonesia, who were interrogating him and his brother Mukhlas, the leader of the JI in Singapore and Malaysia.

Indonesia's Home Affairs Minister Tito Karnavian, who was a senior counter-terrorism official investigating the JI, said in an interview that Indonesian authorities enjoyed good cooperation with Singapore, with intense and robust sharing of information on the threat to the region.

They also built personal relationships, enabling them to communicate informally or pick up the phone when they needed to share intel on threats.

In fact, it was the prospect of a group of trained, vengeful Singapore JI members staging retaliatory attacks against their country that spurred investigators to pursue and bring back JI fugitives.

They followed up on leads obtained through interviews with detained JI members, and ISD field officers kept tabs on the fugitives' local associates to get information on their possible whereabouts.

Senior operations officer Faisal (not his real name) said those who fled had already conducted reconnaissance of targets in Singapore, and could well link up with regional JI members to launch attacks here.

Another concern was the possibility of them building a second generation of JI overseas.

But detecting the fugitives and detaining them was not as straightforward, and often required some creativity.

A senior operations officer, Carol (not her real name), remembers a breakthrough lead on a fugitive who was a senior member of the Singapore JI, after nearly 10 years of tracking him down.

A resourceful ISD officer had befriended an associate of the fugitive, and realised he was in contact with the fugitive. ISD also had suspicions of the fugitive's whereabouts before that.

"We quickly seized this window of opportunity and acted decisively. Arrangements were made for the associate to meet with the fugitive at a hotel during his holiday in the neighbouring country."

They alerted their foreign counterpart, who helped apprehend the fugitive for immigration offences when he showed up.

"I remember the sense of pride and relief I felt when the fugitive was repatriated to Singapore a few weeks after his arrest," said Carol. "The long process of tracking the JI fugitives required significant tenacity, patience and teamwork from all involved."

Another team also worked closely with the families and friends of some fugitives, to persuade them to return home.

Carol said she knew of at least two fugitives who decided to surrender after being convinced by their families to do so.

Another former member, Helmi (not his real name), who was in Malaysia when the ISD was closing in on JI members here, decided to take refuge in Thailand to escape the Malaysian authorities.

He was invited to join a group of JI members who wanted to retaliate against Singapore for detaining their comrades. They began to make arrangements to stage a suicide bomb attack against the Singapore immigration complex and water pipelines along the Causeway.

But the plan never came to fruition. In 2004, Helmi was caught for immigration offences and was sentenced to two months' jail in a neighbouring country. He was then deported and handed over to ISD.

Deputy Commissioner of Police Normah Ishak, head of the Malaysian Special Branch Counter Terrorism Division, said 14 Singaporean JI members had been tracked down and arrested in Malaysia over the years, due to the strong ties between both countries.

All were deported and rearrested by Singapore authorities.

"Both sides continue to exchange information and keep each other abreast of current developments, to ensure holistic coverage of our shared borders," she added.

These relationships across the region meant that about 20 of the known Singapore JI fugitives have been repatriated, except for one - Hassan Saynudin alias Fajar Taslim - who is serving out his jail term in Indonesia for terror offences.