Updated

Five years ago, retired Air Force intelligence officer Kirk von Ackermann became the first of 39 Americans to be kidnapped in Iraq. He's still missing, his wife fearing she'll never see him again.

Besides the personal tragedy, his disappearance and those that have followed have taken on a larger significance. They mark a turning point in terrorist tactics that U.S. intelligence officials say has produced a startling statistic: a 500 percent increase in foreigners taken hostage around the world as militants adopt the methods of the most violent figures in the Iraq insurgency.

Figures compiled by the Defense Intelligence Agency from classified and unclassified sources — provided exclusively to The Associated Press — show that in 2004, some 342 foreign and U.S. hostages were taken by terrorist and insurgent organizations.

By 2006 that number had grown to 501. By 2007 it had jumped to more than 1,500, and it is on track to rise even higher this year, according to Thomas Brown, director of the office that analyzes information about prisoners of war and those missing in action.

His office does not count in the total the kidnapping of a country's own residents by terrorist or insurgent groups — a much more frequent and long-standing practice.

The office gave the AP data providing a more detailed breakdown, including:

• The total kidnappings, some based on classified information.

• The 1,079 foreign kidnappings since 2001 for which the hostage takers are unknown. That smaller number is drawn from public sources and includes cases in which the details of the disappearance are unverified.

• The 747 kidnappings of people traveling or working in foreign countries since 2001 for which the terrorist group responsible is known. Of those, also based on unclassified information, 73 are Americans and the fates of 11 remain unknown.

Those 11 include von Ackermann, who was working for a private contractor and vanished on Oct. 9, 2003, on the road between Kirkuk and Tikrit.

His wife, Megan von Ackermann, said the Army's Criminal Investigative Command told her he was believed to be the victim of an opportunistic kidnapping, not an organized effort, and that the man suspected of being behind it has disappeared.

"What we've got is a presumption of death; that's a certificate that's issued by the State Department," she said in an interview with the AP. "This is what our best guess is. The case is still open. The fact is we'll never really know what happened to him."

Kidnapping as a terrorist tactic has spread rapidly after its spike to 229 in Iraq in 2004 — though the practice has waned somewhat in Iraq since the death in 2006 of Abu Musab al-Zarqawi, the former leader of al-Qaida in Iraq.

In Afghanistan, foreigners are more likely than Americans to be taken, and killed. Since 2001, three Americans have been kidnapped, the most recent in January. Two were released and the third is officially unaccounted for but believed dead.

In the same period, 101 foreigners were kidnapped, 86 of them since 2005. Nineteen have been executed, 10 in 2006 alone.

Iraq has been most dangerous for Americans, who have a better than even chance of being murdered by their captors there — an 80 percent chance if the nine still missing are factored in. Foreigners, kidnapped in much higher numbers, have had a 20 percent chance of execution.

Thirty-nine Americans have been taken hostage since 2003 in Iraq, and 22 are known to have been executed.

Some 495 foreigners were captured in the same period in Iraq, and 51 were executed. Al-Qaida in Iraq and Sunni groups killed 13 Americans and 34 foreigners. Shiite extremists have killed nine Americans and 17 foreigners.

Analysts attribute the different execution rates to several factors, including the U.S. government's refusal to pay ransom. Other governments, particularly those in Europe, privately take a more flexible position. A non-American is more likely to be targeted if the objective is cash, an American if it's for propaganda or terror purposes. U.S. military hostages are almost guaranteed execution.

Citizens of countries that have sent troops to Iraq or Afghanistan also face a higher risk of execution, according to Minwoo Yun, a social scientist at Wheeling Jesuit University who has studied public data on terrorist hostage-taking. In Afghanistan, Indians are more likely to be killed than others nationalities, reflecting the continuing conflict between Hindus and Muslims over Kashmir in Pakistan. In other regions of the world, the casualty difference between Americans and other nationalities is similar, Yun said.

Al-Zarqawi, the slain former leader of al-Qaida in Iraq, made his name with foreign hostage-taking and popularized it worldwide by videotaping his prisoners. Between 2003 and 2006 he released videotapes of 90 captured hostages, 17 of them executed on camera. The practice waned after Zarqawi's death in 2006, as did the number of kidnappings in Iraq.

But it has exploded elsewhere. In Nigeria, there have been 141 foreign hostages taken since 2006, up from just five in 2005. Most are associated with oil facilities. In Somalia, pirates and insurgent groups have taken more than 500 since 2006, up from just nine in 2005, according to the DIA. The upward trend in both countries is expected to continue.

Extracting useful intelligence from these numbers and thousands of other data points is the job of the POW/MIA analytic cell. Created in 2001, it serves two main purposes:

• Compiling and analyzing reams of data to build profiles of terrorist groups worldwide that use kidnapping, noting where hostages are captured, moved, released or executed.

• Predicting where future hostages may be taken, and when.

In 2003, the cell pieced together photos of dead soldiers and a convoy manifest list to determine that two female American soldiers were unaccounted for after an ambush near Nasiriya, kicking off a massive search operation for Pvt. Jessica Lynch and Pvt. Lori Ann Piestewa. Piestewa was killed in the ambush; Lynch was later rescued.

In another 2003 POW case, it accurately predicted that seven Americans would be held at a Baghdad prison. When it was raided, the American prisoners had been moved just hours before, their captors spooked by a nearby, unrelated bombing.

Over the past five years, the cell produced more than 100 briefings on the movements and possible locations of three American contractors who crashed in Colombia in 2003 and had been taken prisoner by the terrorist group FARC. The men were among 15 people rescued in July.

Brown's team is on the trail of 21 hostages now, including 14 unresolved American cases since 1993 and the continuing search for missing American Navy pilot Capt. Scott Speicher, shot down in 1991 over Iraq.