The Obama administration admitted Tuesday that it should not have granted amnesty to an illegal immigrant gang member who was recently charged in the murders of four people.

U.S. Customs and Immigration Services (USCIS) Director Leon Rodriguez admitted in a letter Friday that Emmanuel Jesus Rangel-Hernandez, 19, was granted deferred deportation status in August 2013 under President Obama's Deferred Action for Childhood Arrivals (DACA) program - even though a federal crime database indicated at the time that he was a "known gang member."

"Based on the standard procedures and protocols in place at the time, the DACA request and related employment authorization should not have been approved," Rodriguez wrote, according to The Daily Caller. "Given the fact that the individual was identified as a known gang member, his request should have been denied by the adjudicator."

USCIS revoked Rangel-Hernandez's status a month after he was charged with the February murder of four people in Charlotte, including former "America's Top Model" contestant Mirjana Puhar, reported Fox News.

President Obama, upon unilaterally enacting the DACA program in 2012 and his more recent 2014 amnesty efforts, insisted his actions would result in the ability to better focus efforts on deporting dangerous criminals while allowing law-abiding immigrants to continue living in the U.S. without fear of deportation. But these new revelations call into question those assertions.

USCIS revealed that at least 20 other immigrants who were approved under DACA also had suspected gang ties listed in a federal database.

"This statement by USCIS confirms what we have feared - that USCIS is not doing a thorough job reviewing the individuals who it allows to stay in this country under the President's deferred action program," said Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, in a statement on Tuesday.

"It's no secret that USCIS staff is under intense pressure to approve every DACA application that comes across their desk, and based on this information, it's clear that adequate protocols are not in place to protect public safety... The fact is that this tragedy could have been avoided if the agency had a zero tolerance policy with regard to criminal aliens and gang members."

Rodriguez said in his letter that in order to prevent similar errors from occurring again, he ordered immigration service officers responsible for approving DACA applicants and all members of the Background Check Unit to take refresher training courses, which were held between March 30 and April 10.