WASHINGTON. – On Monday, the Republican Congressman, Michael McCaul, said that U.S. Federal authorities increased the review of student visas to "verify their validity" in response to the Boston attacks in April, which revealed a "serious hole" in national security.

McCaul, Chairman of the House Committee on Homeland Security, said that "the fact that a foreign citizen was able to re-enter the U.S. with what was apparently a valid visa as immigration agents did not see that it was expired, is a big hole in national security."

The congressman was referring to Azamat Tazhayakov, the student who along with Dzhokhar Tsarnaev is alleged to be the ones responsible of the Boston attacks on April 15, and is now being held on charges of obstruction of justice and destroying evidence of criminal investigation.

Apparently, Tazhayakov returned to the United States on January 20, but with a visa that had expired on August 30, 2012, after leaving the University of Massachusetts Dartmouth, where he met Dzhokhar.

In a congressional report released this past week, it precisely indicated that "effect immediately" U.S. Customs and Border Protection Agents must verify student visas every time someone is entering the country.

Immigration officers will now have faster access to computer databases on the validity of student visas granted by the Department of Homeland Security.