From NPR News in Washington, I'm Lakshmi Singh.Law enforcement officials are reporting progress in the investigation of the Boston Marathon bombingthat killed at least 3 people and wounded more than 170.Video of the bombing scene has been keyand the possible suspect has been spotted.However, NPR's Tom Gjelten saysthe FBI is saying that no arrests have yet been made in the case.A senior law enforcement official tells NPRthat video of the spot warns at least one of the bombs exploded,shows a man setting down a bag and then leaving the scene.But the official says that there is not necessary mean that the man is the suspect.We need more than that, the official says.Early press reports say a man has been arrestedand was even been taken to the federal court house in Boston,but the FBI is knocking no reports down on hard.In the statement, the FBI said"contrast to widespread reporting,no arrests have been made in connection with the Boston Marathon attack."Over the past daysthere have been a number of press reports based on information from unofficial sourcesthat have been inaccurate, the bureau said.Tom Gjelten, NPR News, Washington.The FBI is leading an investigation to poison letters that were sent to political leaders.NPR's Ari Shapiro reportsone was addressed to president Obama,and another to Mississippi senator, Roger Wicker.Both of the letters were intercepted before they reached their targets.White House spokesman Jay Carney saysthe FBI is conducting further tests to confirm
