FARS photo claiming to show Roshan and his son on January 11 AP There was no doubt that Mostafa Ahmadi-Roshan was assasinated last week in Iran as he made his way to work at an uranium enrichment facility — the only question that remained was who did it.

The Sunday Times reports they have a Mossad source who says it was his group that pulled off the bombing, and it was a "precursor to a military strike" (via Ha'aretz).

The idea being that should Iran's nuclear facilities be bombed, it will be all the more difficult for them to rebuild without scientists to staff them.

The source says the hit was coordinated months in advance, requiring teams on the ground to monitor Roshan, learn his schedule, and decide where best to eliminate him.

From Ha'aretz:

According to the Sunday Times, Roshan, 32, was monitored from a makeshift control room in a safe house nearby as he was preparing to leave for work. Israeli agents were also watching the entrance to Iranian intelligence headquarters in the city center, when they noticed a number of cars and people running, followed by police rushing into the nearby streets. Another agent monitoring radio traffic between the Tehran police and security forces confirmed unusual activity, said the paper.

The report states that as Roshan’s bodyguard was driving him to Natanz uranium enrichment site, where he served as director, a masked person on a motorbike weaved through traffic, planting a bomb on the car shaped to deliver its full force at the passenger.

Both British and U.S. officials have said that neither country took part in the assasination.