(CNSNews.com) - Shortly after Umar Farouk Abdulmutallab, a Nigerian national, attempted to detonate an underwear bomb aboard Northwest Flight 253 as it approached Detroit from Amsterdam on Christmas Day 2009, the Homeland Security Department's Transportation Security Administration mandated heightened security checks (including full body patdowns) for all nationals of Nigeria and 13 other countries who boarded flights bound for the U.S.

As the New York Times reported on Jan. 4, 2010, this heightened security screening was predicated on the U.S. government’s conclusion that the population of these countries “would more likely include terrorism suspects.”

Yet in the months following the attack on Flight 253, DHS continued to routinely release many of the Nigerians it initially detained in the United States on suspected immigration violations.

Because of DHS’s practice of catching and releasing suspected Nigerian immigration violators, 52 Nigerians ended up becoming fugitives in the United States in fiscal years 2009 and 2010 alone.

These 52 Nigerian fugitives include 15 who DHS caught and released in the 9 months following Abdulmutallab’s attempt to blow up Northwest Flight 253.

They also included two additional fugitives who DHS caught before the attempted Christmas Day bombing then released after it.

DHS defines a "fugitive" as "an individual who has a final order of removal and has absconded."

These facts come from an Immigration and Customs Enforcement (ICE) database of non-Mexican foreign nationals detained by ICE for suspected immigration violations in fiscal years 2009 and 2010. ICE provided the database to CNSNews.com in response to a Freedom of Information Act request.

The ICE database revealed that in fiscal years 2009 and 2010 (each fiscal year beginning on Oct. 1 and ending on Sept. 30), ICE detained a total 1,158 Nigerians for suspected immigration violations. The pace of these detentions was remarkably steady, with 580 taking place in fiscal 2009 and 578 taking place in fiscal 2010.

Of the 1,158 Nigerians ICE detained over the two years, 503 were removed or deported from the United States or voluntarily removed themselves (as of Jan. 5, 2011 when the database provided to CNSNews.com was generated).

Of the 655 who remained in the country, 122 were still incarcerated and 533 had been released.

Of the 533 Nigerians caught and released, only 86 had had their cases terminated in their favor. These included 1 who was granted permanent legal residency, 25 who were granted some other form of relief, 16 whose cases were dropped by DHS and 44 whose cases were either closed administratively or by an immigration judge.

Of the remaining 447 Nigerians who were caught and released and whose cases had not been terminated in their favor, the ICE database specifically states the “case status” and “case category” of only 128. (The “case status” column on the ICE database indicates how a case has been disposed or if it is still active. The “case category” column indicates the grounds on which it is being or has been adjudicated.)

Of the 128 caught-and-released Nigerians for whom the case status and case category is reported in the database, 52 are reported to be fugitives whose whereabouts is unknown.

The other 76 caught-and-released Nigerians for whom the database lists a case status and category include 1 who died, 12 who have been issued an ICE Form I-275 (which begins the process of revoking a visa), and 62 who are awaiting adjudication of their cases.

For the remaining 319 Nigerian nationals that ICE caught and released in fiscal years 2009 and 2010, the “case status” and “case category” columns are simply left blank in the database that ICE provided to CNSNews.com.

According ICE Spokesperson Ernestine Fobbs a blank in these columns indicates the case in question has not yet been resolved and that a number of arrangements might apply to the person in question--including “alternatives to detention.”

The database indicates that DHS did not significantly alter its handling of suspected illegal aliens from Nigeria in the months following Abdulmutallab’s attempted bombing of Flight 253.

In the slightly more than 9 months between Christmas Day 2009 and the end of fiscal 2010, ICE detained 445 Nigerian nationals on suspected immigration violations. As of Jan. 5, only 47 of these 445 remained in detention and only 29 had seen their cases terminated in their favor.

Of the other 369 Nigerians that ICE caught and released between the attack on Flight 253 and the close of fiscal 2010, 1 died, 28 were awaiting adjudication of their cases, and 171 had blanks in their “case status” and “case category” columns.

Fifteen of the Nigerians caught and released in those nine months went on to become fugitives, according to the ICE database.

Two Nigerians detained in fiscal 2010 before the attack on Flight 253 were released after the attack and have since become fugitives.

In total, between the attempted Christmas Day 2009 attack on Flight 253 and Sept. 30, 2010, ICE released 17 Nigerians who became fugitives.

According to the New York Times, the 14 countries whose nationals DHS subjected to mandatory heightened security screening after the attempted Christmas Day attack included Afghanistan, Algeria, Lebanon, Libya, Iraq, Nigeria, Pakistan, Saudi Arabia, Somalia, and Yemen, plus the four nations the State Department as state sponsors of terror: Cuba, Iran, Sudan and Syria.