Like millions before him, Cho Seung-Hui arrived in the United States as a child with parents who were granted permanent residency status.
Cho, the 23-year-old college senior who killed 32 people and then himself Monday at Virginia Tech's campus, was 8 when he and his family arrived in Detroit in 1992, according to the U.S. Citizenship and Immigration Service. The family later settled in a Virginia suburb outside Washington.
Cho's last contact with immigration officials was Nov. 27, 2003, when his legal resident identification, or "green card," was reissued.
After living in the U.S. for 10 years, applicants must renew their identification -- a process that involves immigration officials collecting biometric information and conducting background checks through law enforcement databases, said Chris Bentley, a spokesman with USCIS.
"We would have seen if there was any criminal activity that would have prevented any issue of his green card," he said. "There was none."
Cho appeared very much the typical legal resident, Bentley said. "As a lawful person, you are free to travel around, seek employment anywhere you can, and you are free to study anywhere in the U.S.," he said.
An estimated 8 million people living in the United States are legal permanent residents, about 1.2 million of whom became legal residents last year, according to immigration statistics. Maryland and Virginia are among the top 10 states of residence for new green card holders.
Foreign nationals typically become legal permanent residents by being sponsored by employers or by family members who are U.S. citizens or legal permanent residents.
Others might be eligible for the immigration service's diversity program, which makes green cards available to nationals of countries with low rates of legal immigration to the U.S.
People who have relationships with U.S. citizens are given high priority, while other categories have annual limits on the number of permanent residents accepted.
Most legal permanent residents 18 and older may apply for U.S. citizenship, if they have lived in the country five years and pass a citizenship test.
Legal permanent residents are different from temporary residents, which include students and workers on visas.
While legal residents may qualify for federal and state aid to attend college, temporary visitors do not, according to the U.S. Department of Education.