Western security agencies were most likely behind the killing of an Iranian scientist in an operation that underlines the myriad complications in the conflict over Iran's nuclear programme, analysts say.
Darioush Rezaie, 35, a university lecturer, was shot dead by gunmen in eastern Tehran on Saturday, the third murder of a scientist since 2009. One was killed in a car bomb, the second by a device detonated remotely.
The Iranian government's responses to past such incidents have appeared confused but the Rezaie case has surpassed previous levels, with the authorities speaking in strikingly different voices from the outset.
"Assassinations will continue to be a tool used in this covert war. While it's impossible to tell with certainty whether Rezaie was an active nuclear scientist, his death appears to be another episode in that war," said London-based analyst Ghanem Nuseibeh, founder of Cornerstone Global Associates.
"The Iranian narrative has been confused about Rezaie's work and this adds credence to the speculation that he has been involved in the nuclear programme."
When news of the shooting first came out, semi-official news agency Mehr published information on Rezaie's background which indicated involvement in Iranian nuclear activities that have brought sanctions on the Tehran government by the West.
But the report was then immediately withdrawn by Mehr and Iran's intelligence minister Heydar Moslehi and other officials denied Rezaie had any links to the nuclear energy programme.
Then when parliament speaker Ali Larijani blamed the United States and Israel in a speech broadcast live on state television on Sunday, Moslehi said it was too early to tell.
"We have not found any trace of foreign spy services involvement in Rezaie's assassination case yet," state television quoted him as saying.
Other bodies involved in investigations would normally include the Revolutionary Guards and the office of Supreme Leader Ali Khamenei, and possibly others.
Analysts believe that Iran might wish to play down the accusations of blame as the incident is embarrassing for its security agencies and could become an issue in domestic politics.
"I suspect, just based on what's known in the Iranian media reporting, that Rezaie was assassinated because of his relationship to Iran's nuclear program," said Afshon Ostovar, an Iran analyst based in Washington.
After the initial confusion, Ostovar said he detected "a PR campaign to both downplay the impact of his death on Iran's nuclear programme and to discredit any sense of legitimacy of the assassination".
Several analysts said they believed the killing to have been carried out by US or Israeli agents.
Both countries have said they are prepared to take military action to stop the Islamic Republic becoming a nuclear power. They fear Iran's uranium enrichment programme is designed to take Tehran to the point where it can quickly put together atomic weapons if it wanted to, although Tehran insists the programme is for peaceful purposes.
A US spokeswoman denied any US involvement.
"It's frequent practice for Tehran to accuse the West for these kinds of incidents, and we hope that Tehran is not planning to use this incident to distract attention from what it needs to do, which is to come back into compliance with international obligations," State Department spokeswoman Victoria Nuland told a press briefing.
Asked about Israel's response to the accusations, Defence Minister Ehud Barak said on Sunday: "It's not responding".
Despite public infighting within the Iranian ruling establishment, which has seen President Mahmoud Ahmadinejad and his supporters fall out of favour with Supreme Leader Ali Khamenei, Western analysts see signs that Iran is pushing ahead with plans to develop the means to develop nuclear warheads.
Last month Iran said it would shift production of higher-grade uranium to an underground bunker and triple output capacity. It also test-fired 14 missiles in one day including some it says can reach Israel and US bases in the region.
Iran police chief blames West for crime rise
Western powers are responsible for a recent spike in crime in Iran, the state television website on Tuesday quoted police chief Esmaeel Ahmadi Moghaddam as saying.
"We are witnessing major powers present in the region organising efforts to spread crime and a lack of security in our society," he said after being asked by deputies to explain an increase in crime in recent months.
"Drugs, alcohol, moral decadence, satellite channels and cultural assaults, all officially organised from abroad, are the main causes of crime" in Iran, Brigadier General Ahmadi Moghaddam said.
The authorities do not regularly publish statistics on crime in the Islamic republic but in recent months several cases of murder and rape have made media headlines.
Ahmadi Moghaddam also implicitly blamed the reformist opposition within the regime for the rise in violence, saying that crime "increased after the sedition" movement of 2009.
He was alluding to months of anti-government demonstrations after the disputed re-election of President Mahmoud Ahmadinejad in June 2009.
Ahmadi Moghaddam noted that criminal activity has decreased since the beginning of the year but that statistics were relatively low given the volume of Iran's population, officially estimated at 75 million.
He put the number of premeditated murders committed during the last Iranian year -- March 2010 to March 2011 -- at 1,277, while also confirming "800 to 900 reported rapes" over the past four years.