The BBC's Tehran correspondent, Jon Leyne, looks at the questions raised by the death of an Iranian physics specialist in a bombing on Tuesday.
According to the Iranian media, Masoud Ali Mohammadi was a nuclear scientist, assassinated by counter-revolutionaries, Zionists and agents of the "global arrogance".
The implication is clear - his killing was a Western plot to sabotage Iran's nuclear programme.
But from the start, there were many curious anomalies.
Iranian media were unusually quick off the mark to report the killing, to show television pictures, and to give the sort of details that usually only emerge after hours, days, or weeks in this secretive state.
The state broadcaster described Dr Mohammadi as a "committed and revolutionary" professor - a strange tribute to emerge so soon.
He was also described as a nuclear scientist.
Official and semi-official media blamed counter-revolutionaries, Zionists and agents of the "global arrogance" - Iran's usual term for its enemies in the West.
And a reporter for a government-owned newspaper told the BBC the scientist's death was likely to be a setback for the Iranian nuclear programme - another strange comment in a country where defiance is usually the rule.
But scientists in Britain and the United States pointed out that, from his substantial body of published research, Dr Mohammadi was most unlikely to have been working on Iran's nuclear programme.
His exp... >>>
|نسرین ستوده: زندانی روز
|Saeed Malekpour: Prisoner of the day
|Lawyer says death sentence suspended
|Majid Tavakoli: Prisoner of the day
|Iterview with mother
|احسان نراقی: جامعه شناس و نویسنده ۱۳۰۵-۱۳۹۱
|Nasrin Sotoudeh: Prisoner of the day
|46 days on hunger strike
|Nasrin Sotoudeh: Graffiti
|گوهر عشقی: مادر ستار بهشتی
|Abdollah Momeni: Prisoner of the day
|Activist denied leave and family visits for 1.5 years
|محمد کلالی: یکی از حمله کنندگان به سفارت ایران در برلین
|Habibollah Golparipour: Prisoner of the day
|Kurdish Activist on Death Row