Iran says it has arrested the person who filmed the footage showing a Ukrainian passenger plane being shot down by a missile.
It is believed the person being detained will face charges related to national security.
Flight PS752 was brought down after it took off from Tehran on Wednesday last week, killing all 176 people on board.
Iran has said it was shot down by accident and announced the arrest of several people over the incident.
President Hassan Rouhani said his country's investigation would be overseen by a "special court".
"This will not be a regular and usual case. The whole world will be watching this court," he said in a speech.
Mr Rouhani also stressed that the "tragic event" should not be blamed on one individua
The person detained is believed to be facing charges relating to national security.