The scientist who masterminded Iran’s nuclear program in the 2000s was machine-gunned to death on Friday—but it seems as if the assassination was much more complex than it first appeared. Authorities initially said a truck exploded and then a group of men opened fire on Mohsen Fakhrizadeh, but a top Iranian security official has now accused Israel of using “electronic devices” to remotely kill the scientist. “Unfortunately, the operation was a very complicated operation and was carried out by using electronic devices,” said Ali Shamkhani, the secretary of the country’s Supreme National Security Council. “No individual was present at the site.” Israel, long suspected of carrying out a string of assassinations on Iranian nuclear scientists since 2010, has yet to comment on the attack.