Leonnig is an award-winning investigative reporter who has worked at the Washington Post since 2000, and was part of a team of national security reporters that won the Pulitzer Prize for Public Service in 2014. The Post team's prize was for reporting that revealed the NSA's expanded spying on Americans. Leonnig native of Upper Marlboro in Prince George’s County and daughter of two attorneys, she knows how to make a good argument but is not the argumentative type. Credit goes to her mother, Dolly, for instilling the good manners that continue to serve her well even with the most hardened of Washington insiders. Her first reporting job was in 1989 at The Philadelphia Inquirer.
She later became a staff writer for The Charlotte Observer, where she first reported on city government, later moved to cover the state legislature and eventually became the paper's Washington correspondent. During her time at the Observer, she was a lead reporter on several investigative projects, including one involving Bank of America's use of federal funds to raze low-income housing near its corporate headquarters and another uncovering that Gov. Jim Hunt personally directed state funds to be used to build a major bridge in his rural hometown. Hunt apologized and cancelled the project after the story about his involvement was published.
At the Washington Post, Leonnig first covered the District of Columbia city government and its continuing problems with corruption, and then spent five years covering the federal courts in Washington. Having reported on the Bush administration and issues surrounding detainees imprisoned indefinitely at the Guantanamo Bay detention camp from that federal courts beat, she now writes for the Post's National Desk as part of a team investigating public officials, federal agencies and government accountability.
She has done numerous radio and television interviews, including National Public Radio, The NewsHour With Jim Lehrer, Fox News, and MSNBC. Her coverage of the Bush administration has been cited in many books on the subject.
In 2011, Leonnig and her Post colleague Joe Stephens revealed in a series of stories how the Obama administration pressed to approve a $535 million federal loan to Solyndra, a solar panel manufacturer whose leading investors were tied to a major Obama fundraiser. Their stories were the first to document how White House aides for the senior-most White House advisers pressured Office of Management and Budget officials to make a decision on approving the Solyndra loan in time for a press conference they had tentatively scheduled for the Vice President to announce the funding. The company was one President Obama himself touted in a high-profile visit in 2010, shortly after independent auditors raised concern about whether Solyndra was financially strong enough to remain a going concern.
In 2015, Leonnig won the Pulitzer Prize for National Reporting "for her smart, persistent coverage of the Secret Service, its security lapses and the ways in which the agency neglected its vital task: the protection of the President of the United States."
In 2014, Leonnig was part of the Washington Post reporting team that won the Pulitzer Prize for Public Service for their coverage of the National Security Agency's expanded surveillance of everyday Americans based on former NSA contractor Edward Snowden's disclosures. The team's six months of revelatory work exposed the government's secret collection of records for all Americans' phone calls and electronic communications. The team also uncovered how a secret court had authorized much of the communication collection under secret law. Despite President Obama's claims that the court provided a key check on the NSA's spying power, The Post team revealed how the court's top judges had belatedly learned that the NSA had been violating the court's rules to protect innocent individuals' privacy for years—in fact, from the day the surveillance programs began. The court's chief judge later acknowledged to the Post it had no way to check the NSA's claims that it was properly safeguarding privacy.
Also in 2014, Leonnig was a winner of the George Polk Award for investigative reporting, given by Long Island University, for her 2013 work uncovering a bribery scandal involving Virginia Gov. Bob McDonnell. Along with fellow winners and Post colleagues Rosalind Helderman and Laura Vozzella, Leonnig helped reveal roughly $165,000 in luxury gifts and loans that McDonnell and First Lady Maureen McDonnell received from a prominent Richmond businessman and the couple's effort to use state levers to help their patron's business. Revelations about the series of gifts in exchange for official acts led to the McDonnells' criminal indictment in January 2014.
In 2005, Leonnig was part of a seven-person team that won the Selden Ring Award for Investigative Reporting given by the Annenberg School for Communication at the University of Southern California for a series of articles that uncovered unhealthy levels of lead in the drinking water in Washington, D.C. and problems with reporting water quality across the U.S.
She is also a former Paul Miller Washington Reporting Fellow.