1.   At least one other contaminated letter may be to blame, they said.

2.   A few weeks later, a contaminated letter sent to Sen. Patrick Leahy, D-Vt., was discovered.

3.   Daschle said Tuesday no one on his staff, including the woman who opened the contaminated letter, had tested positive for the sometimes fatal disease.

4.   Even if there were thousands of contaminated letters, he noted, it also appears that thousands of people can safely handle such mail.

5.   Eventually, this could enable investigators, for example, to quickly sort out all mail from Trenton in search of other contaminated letters.

6.   Human infections or contaminated letters, however, can be confirmed through a battery of procedures that take several days to establish definitive proof.

7.   Officials said the letter was postmarked from Trenton, N.J., the same city from which a contaminated letter to NBC News had originated.

8.   Officials suspect she might have brushed against the contaminated letter while there.

9.   People who handled a contaminated letter or were in a contaminated area are prescribed anthrax-preventing antibiotics on that basis alone.

10.   The discovery of the contaminated letter, officials said, appears to have resulted from a striking bit of technological detective work.