Defeated Iranian presidential candidate Mir Hossein Mousavi joined tens of thousands of his supporters on Thursday at a rally in Tehran to mourn the deaths of slain protesters, a witness told selfnews. Mousavi arrived at around 6:00 pm (1330 GMT) in a car in front of the telecommunication building at Imam Khomeini square, the witness said. 'We were sitting in front of the telecommunication building when he came. He got out of the car and spoke to the crowd through a loudhailer,' the witness said, adding that crowds of people had been sitting there for two hours before he arrived. 