Nearly all traffic cameras in Tehran had been hacked by Israel for years, with their images encrypted and transmitted to servers in Tel Aviv and southern Israel. One camera angle proved particularly useful - it allowed Israeli intelligence to determine where bodyguards and drivers of senior Iranian officials parked their personal cars near Pasteur Street, where Ayatollah Ali Khamenei was killed in an air strike on Saturday.

The Financial Times reported, citing two people familiar with the matter, that complex algorithms were used to build detailed dossiers on members of Khamenei's security detail. The dossiers included addresses, hours of duty, routes to work, and - most critically - which officials each guard was assigned to protect and transport. Intelligence officers call this a "pattern of life".

The hacked camera feeds were one of hundreds of different streams of intelligence that helped Israel and the CIA determine exactly what time the 86-year-old Khamenei would be in his offices on Saturday morning and who would be joining him. "We knew Tehran like we know Jerusalem," one current Israeli intelligence official told the FT. "And when you know a place as well as you know the street you grew up on, you notice a single thing that's out of place."

The dense intelligence picture of Tehran was built through Israel's signals intelligence Unit 8200, human assets recruited by Mossad, and massive data sets processed by military intelligence into daily briefs. Israel also used social network analysis to parse billions of data points, uncovering unlikely centers of decision-making and identifying fresh targets to surveil and kill.

Itai Shapira, a brigadier general in the Israeli military reserves and 25-year veteran of its intelligence directorate, described the culture driving such operations. "If the decision maker decides that someone has to be assassinated, in Israel the culture is: 'We will provide the targeting intelligence,'" he said.

Also read: NYT: Israel Decimated Iran's Military and Intelligence Leadership in a Single Strike