The letters, handwritten in red ink on loose-leaf paper and signed "A.Q.U.S.A.," were mailed to 20 newspapers around the country, authorities said. The letters contained the warning: "Hundreds will die. We are inside. You cannot stop us."
A federal law enforcement official familiar with the investigation told The Associated Press that the FBI "does not assign high credibility to the threat" because of the circumstances surrounding the letters, including their brevity and the nonspecific nature of the threat. The investigator spoke on condition of anonymity.
Michael DuVally, a Goldman Sachs spokesman, said the firm was working closely with law enforcement authorities, adding that authorities told the firm they don't believe the threat is credible.
"We take any threat to the safety to our people seriously," DuVally said. "We have a broad range of security measures in place to counter all likely threats and we're monitoring the situation closely."
New York FBI spokesman James Margolin said the bureau was trying to determine the origin of the letters. "All threats are taken seriously," he said.
The letters, postmarked in late June from the New York boroughs of Queens and the Bronx, were being analyzed by FBI and U.S. Postal inspectors at the FBI crime lab in Washington, and at the postal service lab in Dulles, Va., said Tom Boyle, a spokesman for the Postal Inspection Service.
Another investigator familiar with the case told the AP it may be difficult to isolate the fingerprints of whoever sent the letters because others touched the envelopes after they were mailed. The investigator said the letters are believed to have been dropped in mailboxes and not mailed from a post office.
The investigators who spoke on condition of anonymity did so because they were not authorized to discuss the case with the media.
Investigators said they also will be looking for DNA evidence that may have been contained in saliva left when the envelopes were sealed. In addition, they will be examining the postal bar codes routinely stamped on letters to pinpoint exactly where the letters entered the mail stream.
The letters were sent to newspapers in Seattle; Boise, Idaho; Corpus Christi, Texas; Fort Wayne, Ind.,; Bayonne and Newark, N.J., and cities in Vermont, Ohio and North Dakota.
The newspapers notified local law enforcement agencies after receiving the letters and in some cases alerted Goldman Sachs directly, law enforcement officials said. Officials said they have no reason to suspect that the newspapers that received the threatening letters have been targeted.
Jim Chapman, assistant metro editor of The Journal Gazette in Fort Wayne said their paper received one of the letters postmarked Queens on July 2 and immediately turned it over to the FBI.
Goldman Sachs did not receive any of the threatening letters, Boyle said.
Goldman Sachs is based in New York and has offices in London, Frankfurt, Tokyo, Hong Kong and other cities. About 3,000 people work in its 44-story Jersey City, N.J., tower.
It is a federal crime to send threats through the U.S. mail, punishable by up to 10 years in prison if convicted.