The FBI and Capitol Police are investigating the vicious attack of a top Senate staffer at her home last week amid concerns that the assault might be related to her work on the Finance Committee. Emilia DiSanto, chief investigator for committee Chairman Chuck Grassley (R-Iowa), arrived at her suburban Virginia home after work Wednesday about 6:30 p.m. As she was unloading belongings from her car, a 6-foot-1-inch white man dressed in black struck her repeatedly with an unidentified object believed to be a baseball bat. After she screamed to her family inside the house, the assailant fled. DiSanto was transported...