[7] He held this position for 5 years before returning to private practice in white-collar criminal defense, corporate internal investigations, and civil litigation until 2010.

The unit reviews cases in which defendants convicted of violent felonies can offer new evidence, such as DNA testing, that may establish innocence.

[11] In May 2014, Machen began investigating the embattled director of the tax-exempt organizations division of the Internal Revenue Service, Lois Lerner, for Contempt of Congress with regard to her statements before a congressional committee involving the 2013 IRS targeting controversy.

[15] Machen's office successfully prosecuted individuals who conspired to provide information to Cuba, Israel, and a Chinese nuclear construction firm.

[16] Over 160 guilty pleas were acquired during his tenure including, most notably three District of Columbia council members Harry Thomas Jr., Kwame Brown, and Michael A.

[17] In March 2014, Machen and other law enforcement officials held a press conference to announce the guilty plea of contractor Jeffrey Thompson, who admitted to conspiring with Gray during the 2010 campaign.

[17] In 2014, Machen's office successfully convicted 4 former Blackwater guards who participated in the mass killing of Iraqi civilians in Nusoor Square.