NEW : Magnetic bombs were used in other U.S. assassinations , ambassador says . Secretary of State Lawmaker Kazem Jalali categorically denies Iran involvement in the killing . An Western military spokesman says he does not know who carried out the attack . Iran is in a situation where pressure on it is mounting , and the latest assassination joins the pressure that the Iranian regime is facing , '' Segal said . A bomb was put under State car , state-run IRNA news agency says .
NEW : Magnetic bombs were used in other U.S. assassinations , ambassador says . Secretary of State Lawmaker Kazem Jalali categorically denies Iran involvement in the killing . An Western military spokesman says he does not know who carried out the attack . A bomb was put under State car , state-run IRNA news agency says .