When al-Qaeda's men met in Kuala Lumpur in 2000, four of them stayed at Yazid Sufaat's house.

Yazid Sufaat, scientist of Osama bin Laden, released by Malaysia after two years in prison on November 20. He has to carry electronic monitoring equipment, only allowed to move in the area near his home in Ampang district and must stay indoors from 20pm to 6am every day.

Sufaat was born in 1964 in Johor Lama, Malaysia. In 1987, he graduated with a major in biochemistry from California State University, USA, then returned to serve in the Malaysian army as a medical technician and was promoted to the rank of captain before he was discharged from the army. .

In 1993, when the Islamic extremist Jemaah Islamiyah (JI) was established in Southeast Asia, Sufaat quickly joined the group. JI is al-Qaeda ally and the two sides have financial and technical links.

Sufaat's house in Kuala Lumpur was requisitioned as a meeting place for senior al-Qaeda members. Here, the group discussed the conspiracy to carry out the September 11, 2001 terrorist attack against the United States. Sufaat also provided accommodation for two hijackers participating in the 9/11 attacks.

Hambali is JI's military commander, has close ties with al-Qaeda and is often referred to as "bin Laden of Southeast Asia". When al-Qaeda needed a scientist to take over the biological weapons program, Hambali introduced Sufaat. In 2001, Sufaat spent several months studying the anthrax bacteria for al-Qaeda in a laboratory near Kandahar airport in Afghanistan.

According to Professor Zachary Abuza from the National War University in Washington DC, Sufaat has come very close to mass-producing biological weapons. "At the time of 9/11, Sufaat and Hambali were in Kandahar and wanted to own a toxic strain of anthrax," he said.

"They have all the facilities and know-how to mass produce biological weapons. What they don't have is the Ames strain, the most lethal strain of anthrax weapons," he said.

Sufaat also purchased 4 tons of ammonium nitrate for Fathur Rahman al-Ghozi, JI's bomb maker, to plan bombings at US and Israeli embassies, British and Australian High Commissions, schools and commercial buildings. there was an American company in Singapore in early or mid-2002. Singapore broke the plot by arresting 6 people on December 9, 2001 and about a dozen more within a month.

Malaysian police arrested Sufaat in 2002 under the Domestic Security Act (ISA). He was released in 2008, after Malaysia's Interior Minister announced that he had "renovated enough".

Sufaat was arrested a second time in 2013 for recruiting new members for the self-proclaimed Islamic State group (IS) in Iraq and Syria. Yazid was imprisoned for 4 years in Tapah prison.

In December 2017, Sufaat was arrested again under the Counter-Terrorism Prevention Act (POTA) after authorities discovered he recruited al-Qaeda members while in prison. The law allows Malaysian authorities to hold a suspect without trial for two years.

Ayob Khan Mydin Pitchay, the head of the Malaysian police's counter-terrorist division, said Yazid remained a security threat after his release.

"His continued involvement in terror-related activities after his release in 2008 and also recruiting his fellow inmates at detention in Tapah prison shows that he has no regrets," Ayob said.

But anti-terrorist expert Ahmad El-Muhammady, who spoke to Yazid in prison in November 2016, believes he will not repeat the offense. "I noticed his exhaustion and loneliness. He just wanted to go home, immediately," Ahmad said. Yazid is married and has three children.

But when asked if terrorist groups would come to Yazid because he was a biochemical scientist, Ahmad replied "they can".

"The question is, does he want to sacrifice his freedom after a long time away from his beloved family? According to what I have observed, he will not," Ahmad said.