For Jihadi John, death could not have been more different than for his victims. While his hostages suffered unimaginable horror as he beheaded them, for him the end came instantaneously.
British and US intelligence agencies had for more than a year been trying to gain live information on the whereabouts of the masked man whose first victim, the American journalist James Foley, was murdered in a video posted on YouTube in August 2014.
Their efforts finally paid off shortly before midnight on Thursday, when intelligence pinpointed the jihadist to a car in the centre of Raqqa, Syria, within a short walk of ISIL's headquarters in the city's old governorate building.
Mohammed Emwazi - his name was finally confirmed by David Cameron for the first time yesterday - is understood to have been located by either MI6 or GCHQ, either through a human source on the ground or by monitoring his communications. The intelligence was passed on to the Pentagon, enabling the operators of an armed Reaper drone in the sky above Raqqa to spot the car in which he was travelling.
At 11.40pm local time (8.40pm GMT) the order to kill was passed to the drone operators based at Creech Air Force Base in Nevada controlling aircraft launched from a base in Iraq.
Controlling their drone via a satellite link, and using a second Reaper as a "spotter" aircraft, they selected their target and released a Hellfire missile from 10,000ft. Experts say the Reaper may have been several miles away, invisible in the night sky. Its missile, travelling at Mach 1.3 (995mph) arrived at such speed that Emwazi would have known nothing before it struck. At 11.51pm, the car, and its four occupants, were blown to pieces.
The result was described by a US official as a "flawless" strike, a "clean hit" that "evaporated" Emwazi, with no collateral damage. "We are 99 per cent sure we got him," the official said.
The Pentagon disclosed that a British drone was also involved in providing additional "eyes in the sky".
Unconfirmed reports suggested one of the others killed was another of the four British jihadists nicknamed "The Beatles" by their captives because of their English accents. Emwazi, 27, was given his nickname after John Lennon.
Emwazi's death, if confirmed, was doubly symbolic. Not only was Isil's main propaganda tool neutralised, but the strike was within sight of two of the locations most strongly identified with the terrorist group. The missile strike happened in or next to Clocktower Square, the roundabout where Isil carries out public executions. In 2012, it was the location of protests against Bashar al-Assad, the Syrian president, as a popular uprising spread across the country. But by the following year, Isil had seized control, and video footage from May of 2013 shows three rebel soldiers, blindfolded with a green rag reminiscent of the colours of the revolution, before being shot dead. Emwazi is understood to have been travelling from the Isil headquarters. He may also have been living in the building.
Rami Abdulrahman, director of the Syrian Observatory for Human Rights monitoring group, said: "All the sources there are saying that the body of an important British jihadist is lying in the hospital of Raqqa. All the sources are saying it is of Jihadi John."
A senior US official said that the drone strike was the result of "persistent surveillance" and that the Pentagon knew it was targeting Emwazi when the shot was taken. Drones fly routinely for 16 hours or more, and the drone that killed Emwazi could have been circling overhead for several hours, waiting for an opportunity. It is likely to have stayed overhead afterwards to see if anyone got out of the car alive.
Britain and the US had always maintained they were working non-stop to find Emwazi, but the apparent extent of their surveillance capabilities over Raqqa had not been clear until now.
The strike suggests Emwazi was under tight surveillance, combining informants with sophisticated technology.
The hunt for Mohammed Emwazi began at the end of 2012, when the security services first suspected he was in Syria. He had been reported missing by his family in August of that year, having left the family home in Queen's Park, north London, and lied about where he was going.
Jihadi John became a top priority for MI6 after his video of Foley's beheading, titled "A Message to America", was posted online last year. The first step was to identify the masked, black-clad figure in the footage. With only his eyes visible, intelligence officers on both sides of the Atlantic examined other clues, primarily his voice and accent, but also his skin colour, height, physique and vein patterns on his hands. By Sept 14 last year, his identity was known to the UK and the US.
British and American special forces operating in Syria for the past year have been gathering human intelligence on senior jihadists, paying informers and carrying out snatch raids on low-level commanders for interrogation.
Raqqa, however, has proved impossible for them to infiltrate, so instead an RAF Rivet Joint spy plane, based at Al Udeid Air Base in Qatar, has "hoovering up" calls and messages for analysis by spies. Much of the communications chatter was analysed at Ayios Nikolaos, a listening station in Cyprus and the largest British overseas spy base. Manned by military intelligence officers working for GCHQ, its highly sensitive dome shaped radars have the capability to "look out" over the horizon for up to 400 miles and pull in information from British warships and submarines deployed in the region. Despite reports that Emwazi had fled to Libya or had been expelled from Isil, the intelligence agencies remained confident he was still in Raqqa, even though he went quiet after his last beheadings, of two Japanese hostages in January.
An air strike last month targeting a Denis Cuspert, a German associate of Emwazi, may have been the first sign that Britain and the US were hot on his trail. David Cameron said both countries had been working "literally around the clock to track him down". He added: "This was a combined effort. And the contribution of both our countries was essential."