This is AP News Minute.Federal officials are denying that a suspect is in custody in the Boston Marathon bombings.A law enforcement official had told several media outlets that a suspect was in custody.But the FBI and the U.S. attorney's office in Boston dispute that.The FBI says the letters that were sent to President Barack Obama and to Mississippi Senator Roger Wicker are relatedand both were postmarked more than a week ago in Memphis.The agency says the substance in both letters has tested positive in preliminary tests for poisonous ricin.It's the latest twist in the case of a north Texas prosecutor and his wife found shot to death in their home two months after an assistant prosecutor was gunned down.Authorities have now charged the wife of a former justice of the peace in the three killings.Kim Williams is being held on $1 million bond.And Britain is saying goodbye to former Prime Minister Margaret Thatcher.Dignitaries from around the world gathered at St. Paul's Cathedral in London and the public lined the streets to catch a glimpse of Thatcher's coffin.Nicole Grether, the Associated Press with AP News Minute.