Long after they were ordered out of the country, thousands of criminal aliens from places like China, Cuba, Vietnam and Pakistan remain free in the United States to commit new crimes because their home countries refuse to take them back

For years, this unique problem percolated under the political radar. But recent crimes by immigrant felons have lawmakers scrambling to punish nations that refuse to repatriate their own citizens. The Obama administration and many Democrats in Congress, however, are blocking punitive legislation, preferring to let the State Department handle the issue diplomatically. Rep. Ted Poe, R-Texas, is leading the charge in Congress to change the law, pushing to withhold visas to nations that refuse to take back their own. Under a 2001 Supreme Court decision, U.S. immigration officials are only permitted to hold someone for six months after their incarceration. So when a home nation refuses to take back their national, the United States is required to release them - no matter what they've done. The issue recently came to Poe's attention after three especially heinous crimes were committed by men ordered deported years ago. In June 2012, a judge sentenced 22-year-old Shafiqul Islam, a Bangladeshi national, for the murder of 73-year-old Lois Decker. "This man was a dangerous criminal," said Hudson New York District Attorney Paul Czajka. "He should not have been in the United States. At the very least, he should have been in detention." Islam murdered Decker after serving a year for sexually assaulting a child. After his release from prison, a judge ordered Islam deported. Bangladesh, however, refused to take him back. Because of the 2001 high court ruling, Islam stayed in the country. More than 50,000 criminal alien immigrants ordered deported remain in the United States. Those nations with the highest numbers, in order, are: Cuba, China, India, Pakistan and Vietnam.