By Robert Windrem, NBC News Producer

Al-Qaida deputy Ayman al Zawahiri appeared in a new propaganda video late last month, lamenting the killing of a high-ranking member of the terror network. Not that long ago, analysts at the CIA would have combed the video for hidden messages--possible “go signals” for terrorist attacks.

Was there something sinister inserted in the Koranic verse at the beginning of the tape, they might wonder, or did the video itself mask an embedded message? Analysts still do textual and video analysis of Al Qaida statements, but the likelihood that messages were secreted in the video is not as high as once thought.

Why? Credit cyber-security advances. U.S. intelligence officials and other terrorism experts say that Al Qaida and related jihadist organizations have mastered cyber security in ways that many terrorism analysts find impressive, vexing and troubling.

By Jim Popkin, NBC News Senior Investigative Producer

On the FBI’s Kids’ Page Web site, young G-Men-in-training are urged to “go on an undercover assignment” to keep “Special Agent Bobby Bureau” from blowing his cover.

But on the mean streets of Washington, D.C., the FBI doesn’t always seem to practice what it preaches.

Take the house, pictured below, which is located directly across the street from the embassy of one of our former Cold War adversaries. Most of the time, the large skylights in the attic of the house appear opaque, as seen here:

By Jim Popkin, NBC News Senior Investigative Producer

The tax returns for Sen. Barack Obama and his wife, Michelle, offer new insights into the power couple's rising fortunes. They chronicle the candidate's rise from state legislator to U.S. senator and beyond. 

The tax returns are dated between 2000 and 2006, showing a steep increase in family income.

For example, the first return indicates that the Obamas' combined income was $240,505. That included Obama's salary as a young state senator in Illinois, $16,500 in fees as a "foundation director/educational speaker," and his wife's salary as a hospital administrator.

But just six years later in 2006, the Obamas' combined income was $983,826, some $740,000 more. Obama had become a U.S. senator by then, making about $165,000 a year, and his wife's income from the University of Chicago Medical Center had sharply climbed to about $265,000 a year.

Obama's book-writing career had also become profitable, earning him $551,240 in author fees for 2006 alone.

Click here to read the full story. Click here to see the PDF.

By Robert Windrem, NBC News Producer

When the United States learned that it had inadvertently sent four critical missile warhead components to Taiwan recently, it quickly told Beijing.

It was not just a courtesy. The United States, China and Taiwan have been involved in a dance for nearly 40 years trying to keep the island nation from getting nuclear weapons. If Chinese intelligence had learned of the shipment and believed the components were not shipped inadvertently, it would have no doubt created a crisis of confidence in U.S. assurances that Taiwan will not be permitted to go nuclear.

For 40 years, the U.S. has threatened, cajoled and spied on Taiwanese nuclear programs. The spy story alone says a lot about how high a priority the U.S. has placed on those efforts.

In ordinary circumstances, the 1988 defection of Chang Hsien-y, a colonel in the Taiwanese military, would not have been especially notable, particularly given the number of other defections that occurred during the Cold War. One day, Chang, his wife and their three children simply boarded an airplane at a former U.S. air base in a remote part of the Republic of China (Taiwan) and disappeared into thin air.

By Jim Popkin and Libby Leist, NBC News

Two of the government contractors who accessed Sen. Barack Obama's passport records worked for a Virginia-based firm called Stanley, Inc., the company said in a statement. A third contractor who looked at passport information for Sen. Obama and Sen. John McCain worked for a company called The Analysis Corporation, the State Department said.

"Two Stanley subcontractor employees were involved in the unauthorized access of Senator Barack Obama's passport files," a Stanley, Inc., spokeswoman said. "In each of these instances the employee was terminated the day the unauthorized search occurred."

"While this is a rare occurrence, we regret the unauthorized access of any individual's private information," Stanley spokeswoman Joelle Pozza added.

By Jim Popkin, NBC News Senior Investigative Producer

Former First Lady Hillary Rodham Clinton's calendar entries are full of unexplained private meetings on key dates when she and President Clinton were fending off a variety of scandals, the newly released White House records show.

Take Jan. 21, 1998. That's the day when most Americans first learned, courtesy of the Washington Post, that President Clinton had had a relationship with Monica Lewinsky. Mrs. Clinton's calendar entry shows that she left the White House at 7:25 pm that evening and returned 25 minutes later. The National Archives, which released the 17,484 calendar pages today, has excised the reason for the brief trip and the names of any of the people whom Mrs. Clinton may have met. The Archives, working in consultation with President Clinton's representatives, cite privacy concerns in blacking out all details of the trip.

By Jim Popkin, NBC News Senior Investigative Producer

Former top aides of Ahmad Chalabi now admit in a new book that they believed that the defectors who Chalabi and his group introduced to Western media and to U.S. intelligence agencies were in some cases providing misleading information about Saddam Hussein and his access to weapons of mass destruction. Chalabi, the charming Iraqi exile who became the darling of American neo-conservatives, helped convince the Bush Administration that Saddam Hussein had WMDs and should invade Iraq.

The new book, “The Man Who Pushed America to War,” was written by NBC News Investigative Producer Aram Roston. Roston chronicles how Chalabi and his group, the Iraqi National Congress (INC), provided sketchy defectors to news media organizations and to US intelligence agencies who embellished their accounts of life under Saddam or lied for dramatic effect. "Chalabi's INC, even where it did not directly plant false information about Saddam's links to terrorists and WMDs, believed that, in many cases, it was false," Roston writes.

By Jonathan Dienst, WNBC Investigative Correspondent
 
The FBI and Homeland Security officials revoked Governor Eliot Spitzer's security clearance early this week as the criminal investigation into Spitzer's alleged use of prostitutes broadened, according to officials familiar with the case.  As a result, Spitzer no longer has access to classified intelligence and security briefings, federal officials told WNBC on condition of anonymity.  A spokeswoman for Spitzer did not return calls for comment.
 
Spitzer's security clearance was pulled on Tuesday, just one day after his alleged connection to the alleged prostitution ring became public. One federal source said Lt. Governor David Paterson is now being cleared for security briefings. 
 
Spitzer still can be told of potential threats, such as the new but uncorroborated Al Qaeda threat against Wall Street and other financial institutions, in order to help deploy resources if necessary.  This latest non-specific threat information about New York suggests a possible attack sometime in March, officials have said. 

By Lisa Myers and Rich Gardella, NBC News Investigative Unit

This post is an update to an earlier version from Wednesday, March 12. See the latest on this investigation here.

Two U.S. senators sent out a new round of letters today to some of the nation’s most high-profile televangelists, urging them to turn over key financial records. The senators told the ministries that they want to know how their “non-profit organizations are structured and operate,” amid allegations that some of the televangelists have misused church funds to enrich themselves.

One of the letters was mailed today to televangelists Randy and Paula White, who founded the Without Walls International Church in Tampa 16 years ago, calling it "the perfect church for people who are not."

By Pete Williams, NBC News Justice Correspondent

It's a staple of investigating a shooting: Find the bullets and spent cartridges, look for scratches and indentations left on the evidence, and check them against bullets fired in a crime lab from a suspect's gun. Such ballistic fingerprints are used in thousands of criminal investigations every year. And several hundred police departments nationwide have computer systems to check recovered casings and bullets against a national database of crime scene evidence and guns.

But a new report recommends against radically expanding this system by generating a database of the marks left by every new handgun sold or imported in the US. Such a concept has been repeatedly suggested by members of Congress, to create the ballistics version of the national fingerprint database, and the Justice Department asked the National Academies of Sciences for an evaluation.

By Jim Popkin, NBC News Senior Investigative Producer

In a bulletin released Friday to U.S. law enforcement officials, the Transportation Security Administration (TSA) is warning of “continued strong terrorist interest” in targeting mass transit systems in the U.S. The 10-page threat assessment, labeled “Unclassified/For Official Use Only” and obtained by NBC News, cautions that the “U.S. mass transit and passenger rail systems are vulnerable to terrorist attacks because they are accessible to large numbers of the public and are notoriously difficult to secure.”  Previous rail attacks in Madrid, London and Mumbai “could inspire terrorists to conduct similar attacks in the United States,” the report adds.

However, the authors of the intelligence analysis make clear that there are no known, immediate dangers. “At this time, there is no credible intelligence regarding specific plans by any extremist groups or individuals to perpetrate an act of terrorism against the U.S. mass transit system,” they write.