U.S. congressional police clear parts of two Senate office buildings Wednesday over concerns over suspicious letters and a package.<br/> <br />Officials are looking into a suspicious package and envelopes and are questioning an individual in that matter. Tests on one suspicious item came back negative and one building was reopened.<br/> <br />White House spokesman Jay Carney says there are also concerns over a letter address to President Barack Obama.<br/> <br />(SOUNDBITE)(English) JAY CARNEY, WHITE HOUSE PRESS SECRETARY SAYING:<br/> <br />"There was a letter sent to -- addressed to the President that at an offsite mail facility was noticed to have contained a suspicious substance, and tests were undertaken. "<br/> <br />In Boston, authorities may have made a breakthrough in the investigation the Marathon bombing that killed three people and injured 176.<br/> <br />Sources tell Reuters investigators believe they have identified a suspect from video and an official announcement is expected later.<br/> <br />This as the
