Ibrahim Hassan Al Asiri has built a reputation as Al Qaeda's bomb-making savant one potential near miss at a time - explosive-rigged underwear aboard a Christmas flight to the US in 2009, printers fitted with high-grade explosives the following year and now possibly a metal-free device that could avoid airport detectors.
Before those failed attempts, he staged an even more audacious attack by turning his own brother into a suicide bomber in a mission that injured Saudi Arabia's top counterterrorism official. It was later decried by the US State Department for its "brutality, novelty and sophistication".
"You tyrants ... your bastions and fortifications will not prevent us from reaching you," said an Al Qaeda statement that claimed responsibility for the August 2009 blast in Jeddah.
This appears to be the essence of Al Asiri's plots as one of the leaders of the Yemen-based Al Qaeda in the Arabian Peninsula, or AQAP.
A pattern has emerged of explosive expertise channelled into designs using a smuggler-style stealth and innovation to try to outwit security forces and spy agencies.
US authorities are investigating the latest device believed to be the work of the Saudi-born Al Asiri or one of his students after it was uncovered during a CIA operation last week.
It was described as a refinement of the underwear bomb that failed to detonate aboard a jetliner over Detroit on December 25, 2009.
The twist this time was an absence of metal, which could have made the device undetectable by conventional airport scanners.
"It was a threat from a standpoint of the design," said John Brennan, counterterrorism adviser to the US president, Barack Obama.
Al Asiri, 30, arrived in Yemen in 2006 after being jailed by Saudi officials during crackdowns against militants.
"They put me in prison and I began to see the depths of [the Saudi] servitude to the Crusaders and their hatred for the true worshippers of God, from the way they interrogated me," he is quoted as saying in the September 2009 issue of Sada Al Malahem, or Voice of Battles, an Arabic-language online magazine put out by Al Qaeda's branch in Yemen.
His younger brother, Abdullah, also made the trek to Yemen as they turned their backs on their father, a four-decade veteran of the Saudi military.
In Yemen's rugged northern mountains, they met with a Yemeni militant, Nasser Al Wahishi, a former aide to Osama bin Laden, and became the nucleus of the new Al Qaeda affiliate, said the magazine's account, which could not be independently confirmed.
They later brought in the US-born cleric, Anwar Al Awlaki, as a powerful propaganda voice in the West. Al Awlaki was killed in a US air strike last September.
US intelligence officials initially believed Al Asiri also was killed in the attack, but the suspicions were proved wrong several weeks later.
In August 2009, Al Asiri was linked to an elaborate scheme to strike at the heart of the Saudis' intelligence services. His brother, Abdullah, posed as a disenchanted militant wishing to surrender to high-ranking officials in his homeland. A Saudi royal jet was dispatched. To avoid detection, the explosives where reportedly hidden in his rectum or between his legs.
Once inside the Saudi intelligence offices in Jeddah, he detonated the device near his target - the deputy interior minister, Prince Mohammed bin Nayef. His father, Prince Nayef ,ran the ministry and would later become the heir to the throne.
Prince Mohammed was slightly injured in the suicide blast. The bomb used an industrial explosive known as PETN, or pentaerythritol tetranitrate, the same material used in 2001 by convicted shoe bomber Richard Reid when he tried to destroy a trans-Atlantic flight.
It would become a signature element of Al Asiri's plots, according to intelligence analysts.
After the failed Christmas 2009 bombing, investigators pulled Al Asiri's fingerprint off the bomb hidden in the underwear of the Nigerian-born suspect, Umar Farouk Abdulmutallab, aboard the Northwest Airlines flight.
Less than a year later, Al Asiri was linked to the discovery of printer cartridges packed with PETN and sent by international courier with Chicago-area synagogues listed as the destination. The explosive-rigged packages - believed powerful enough to bring down a plane - were pulled off airplanes in England and the UAE.
Al Asiri became a major focus of America's anti-terrorism efforts. In March 2011, Washington officially designated him as a wanted terrorist, calling him the primary bombmaker for AQAP. It also presumably puts Al Asiri among the chief targets on the US hit list.
Last month, US officials expressed concern that Al Qaeda "intends to advance plots along multiple fronts, including renewed efforts to target Western aviation", according to a joint intelligence bulletin circulated by the US Northern Command, the FBI and Homeland Security.
While Al Asiri has been dubbed the master bombmaker of Al Qaeda's Yemen franchise, it may be wrong to label him the linchpin of their ability to strike with explosives, said Gregory Johnsen, a Yemen expert at Princeton University.
"It is safe to assume that in the nearly six years he has been in Yemen, he has trained other individuals to replace him if he were to be killed," Mr Johnsen wrote on his blog on Tuesday. "It is unlikely that Asiri is the only bombmaker AQAP has within its ranks - he is just the only name we know."
