they want to make it look like the west and Israel did it. Maybe he was going to talk and the mullahs needed to deflect world opinion to their advantage. He was lower lever operator on their program but his opinion would affect western opinion.The mullahs intentions are out in the open. They killed this poor man and are trying to throw blame which is in their Hadith.
UN warns Turkey against calling buffer a 'safe zone' unless guarantees civilians' safety (Reuters)
from the article: 'We will avenge Israel over murder of Iran nuclear scientist'