WASHINGTON (WUSA9) -- Federal investigators are looking into another threatening act. This one was targeting a Capitol Hill lawmaker.

Wednesday morning, there's word a suspect is in custodyfor theletteraddressed to the office of Mississippi Senator Roger Wicker that tested positive for ricin, a potentially deadly poison. Capitol Hill mail is screened off-site, so theletter did not reach the Senator's office. Mail has been screened off-site since the anthrax scares of 2001 and 2004 when anthrax-laced letters reached the Capitol building.

Senator Wicker released this statement Tuesday evening acknowledging the suspicious letter:

"This matter is part of an ongoing investigation by the United States Capitol Police and FBI. I want to thank our law enforcement officials for their hard work and diligence in keeping those of us who work in the Capitol complex safe. Gayle and I appreciate everyone's thoughts and prayers."

Authorities do not know if there is any connection to the terror attack in Boston. Some lawmakers say it's unlikely there is a link.

Read or Share this story: http://on.wusa9.com/1iKMGuj