Haaretz picks up a story from the Stratfor Web site, run by former intelligence agents. Like all intelligence, this should be considered educated speculation, not fact:
A senior nuclear physicist involved in Iran's nuclear program who died under mysterious circumstances two weeks ago was killed by the Mossad, according to a report released in a U.S. website this weekend....
Professor Ardashir Hosseinpour, a world authority on electromagnetism, was until recently working on uranium enrichment at the facility in Isfahan, one of the central processing sites in Iran's nuclear program.
The physicist died January 18, but news of his death only emerged six days later in two Iranian media outlets.
A report released this weekend in Stratfor.com stated that the Mossad was behind Hosseinpour's death.
The report said the physicist died from "radioactive poisoning" as part of a Mossad effort to halt the Iranian nuclear program through "secret operations."
The site indicates that in the late 1970s and early 1980s, the Mossad was involved in the deaths of scientists involved with the Iraqi nuclear program. At least three scientists were killed in those operations.
A website of expatriate Iranian communists said that several other scientists were killed or injured in the operation to kill Hosseinpour at Isfahan, and given treatment at nearby hospitals....
Both news items said Hosseinpour died from "poison gas."
Radio Farda - a Persian-language station operated by the U.S. government - said several days ago that the scientist died of "smoke inhalation."