The new title at your link (FYI): “Iran: Slain man was student, not nuclear scientist” ;-)
Ex-IAEA official says physics professor Darioush Rezaei, who was assassinated in Tehran, was indeed an atom scientist.
And:
An official, from a member nation of the Vienna-based International Atomic Energy Agency, verified that the victim was named Rezaeinejad, but said he participated in developing high-voltage switches, a key component in setting off the explosions needed to trigger a nuclear warhead. An abstract seen by the AP and co-authored by Rezaeinejad appears to back that claim.