He was appointed by President George W. Bush as the United States Attorney for the District of New Mexico in August 2001 and confirmed by the U.S. Senate in October 2001.

A review of the matter released by the U.S. Department of Justice Inspector General in October 2008 found that his firing had not been performance-related but was politically motivated.

[3] In October 2008, Iglesias was re-activated by the Navy as part of a special prosecution team for Guantanamo detainees suspected of committing terrorism and war crimes.

In 2009, Iglesias was named as an honoree to Esquire magazine's annual "Best and Brightest" issue for his work as a terrorism prosecutor with the Defense Department's Office of Military Commissions.

In 1986, he was one of the members of the legal team that was the inspiration for the film A Few Good Men, with Tom Cruise and Jack Nicholson, a case involving the assault of a fellow Marine at their base in Guantanamo Bay, Cuba.

[9][10] Iglesias headed a panel that advised the U.S. Attorney General John Ashcroft on border and immigration matters.

Weh was dissatisfied with Iglesias due in part to his failure to indict New Mexico State Senator Manny Aragon (D) on fraud and conspiracy charges.

Iglesias testified before Congress in March 2007, stating that Senator Pete Domenici (R-N.M.) and Representative Heather Wilson (R-N.M.) called and urged him to rush indictments against Aragon prior to the November 2006 election.

Nevertheless, Iglesias "had been heralded for his expertise in that area by the Justice Department, which twice selected him to train other federal prosecutors to pursue election crimes" and was "one of two chief federal prosecutors invited to teach at a 'voting integrity symposium' in October 2005… sponsored by Justice's public integrity and civil rights sections.

In response to this charge, Iglesias stated that the reason for these absences was his mandatory service as part of the Naval Reserve.

In 2008 Iglesias wrote (with contributor Davin Seay) In Justice: Inside the Scandal That Rocked the Bush Administration.

"[19] In October 2008, a report by the Department of Justice's Inspector General found that Iglesias had been wrongfully dismissed because he had refused to pursue prosecutions against the Democrat-linked community organization ACORN and a prominent New Mexico Democrat.

The Inspector General's report says that Senator Domenici's complaints were the "primary" reason Iglesias was fired.