Senator Charles Grassley says the FBI’s failed investigation of a 2001 bio-terrorism attack on congress could signal bigger problems.

Five years ago, a letter laced with a deadly strain of anthrax was sent to the Washington office of Senator Tom Daschle. Grassley says he’s concerned the FBI hasn’t solved the case. But he’s even more unhappy that they refuse to brief congress on the investigation. Grassley sees only one reason for the silence: “If there were some sort of secret thing that was bringing them close to somebody and they didn’t want to let them know they were hot on somebody’s trail.”

But Grassley says the FBI could make that clear in a report, thereby giving Congress an update and showing they were making progress. Grassley, who is a Republican, says he thinks government should be “transparent” and citizens have a right to know what’s happening particularly when FBI “headquarters is involved and trying to cover up what FBI agents at the grassroots are doing and they’re worried about the public relations of the FBI and that’s when they wind up getting egg on their faces.”

Grassley charges that the secrecy is proof that the culture of the FBI is not changing like it should be, or as he’s been promised. Grassley’s sent a letter to U.S. Attorney General Alberto Gonzales requesting numerous documents and a full briefing on the anthrax investigation. Grassley, who’s long been a critic of the FBI, says its refusal to submit to congressional oversight has resulted in an inability to prevent crime and terrorism, and has led to misconduct by senior staff members.