Who killed professor Ali- Mohammadi?

Dr. Masoud Ali-Mohammadi, a professor of physics at the University of Tehran, was assassinated in front of his home in northern Tehran on Tuesday. Reports indicate that a motorcycle parked next to his car held a bomb that was set off by a remote control device.
State media, including the Islamic Republic News Agency and Fars immediately declared that professor Ali-Mohammadi was a nuclear physicist and a supporter of Velayat-e Faghih (the  guardianship of the Islamic jurist, i.c the supreme leader, ayatollah Ali Khamenei), and blamed Israel, the United States, and "their lackeys" for orchestrating the assassination.
Students, friends and colleagues, however, said that the professor's views had changed of late. In 1979, while studying at the university of Shiraz, he had supported  the Iranian revolution. But lateron he became a supporter of the reformists. He had said that he voted for the reformists in the elections for the 8th Majles (parliament) in 2008, and also in the in fall 2006 elections for Tehran's city council. More recently, he was one of 240 academics who signed a declaration of support for Mir Hossein Mousavi before the June 12 election. Muhammad Sahimi writes on his blog Tehran Bureau:

A former student of his said that on June 15 (when the huge demonstrations against the rigged presidential election of June 12 broke out) he was at the gathering of the members of the Muslim Student Association of the Faculty of Sciences. At that time, someone from Mousavi's headquarters had called to caution them that security forces had orders to shoot demonstrators, if necessary. He said that Professor Ali-Mohammadi told him, "Young man, do not be scared. We must resist them [the hardliners]. A bullet hurts only at the beginning." According to this student, Professor Ali-Mohammadi then arranged for a bus to take him and many of his students to the demonstrations.
According to a statement that was issued by a group of physics students at the University of Tehran, Professor Ali-Mohammadi was one of the leading academics who stormed the University Chancellor's office to demand an investigation into the June 15 attack on the university when several students were murdered and many more were injured.
Several other students have stated that Professor Ali-Mohammadi had organized debates on the national crisis at the University of Tehran. He had apparently told his students that "they" [the hardliners] had ordered him to put an end to such activities, but that he was going to press on despite their demands. The last of such debates had occurred on January 5, in which he had urged students to come up with a scientific and practical solution to the Iranian crisis. All of his speeches have reportedly been recorded and can be used as evidence to refute the hardliner's propaganda that he was one of them.
A source in Tehran told the author that Professor Ali-Mohammadi had worked with the Islamic Revolution Guards Corps (IRGC) on several projects in the past. This source said that given Professor Ali-Mohammadi's extensive knowledge of the IRGC's activities and his recent new-found support for the reformists and Mousavi would have made him a potential target for the IRGC.

 This last fact, his past involvement with the Revolutionay Guards, makes it less likely that Israel was behind the murder. The more so, since professor Mohammadi was specialized in quantum physics and had no links with the Iranian nuclear program. In the past Israel was linked to a number of assassinations of nuclear physicists or ballistic experts in Arabic an Middle Eastern countries,  the site Four Winds cites scores of cases. In the case of Iran there was in 2001 the murder of Mahmoud Mimand, the man in charge of Iran's ballistic missile program, who was shot in his office in Tehran, and in 2007 the murder of the nuclear scientist Ardeshir Hassanpour. Both were ascribed to the Israeli Mossad. But Ali-Mohammadi? It seems highly unlikely.