The Pulitzer Prize-winning journalist Sari Horwitz has been suspended by The Washington Post for plagiarism.
Horwitz was suspended for three months after she was accused of copying "substantial" parts of a piece in the newspaper Arizona Republic about January's shooting of Congresswoman Gabrielle Giffords.
The Post's executive editor, Marcus Brauchli, apologised "for this serious lapse". The paper stressed that it had found no other evidence of plagiarism in Horwitz's work.
"Plagiarism has long been one of the most serious ethical violations in journalism," the paper's website said. "Reporters often cite other news sources for information that they haven't gathered themselves, but the standard practice is to paraphrase the material and attribute the information to its source."
The case came to light earlier this week when Randy Lovely, the editor of the Arizona Republic, emailed Brauchli. "I have great respect for the Post," said Lovely. "At the same time, our reporters worked hard to gather this information, and it's not right to simply take it."
Horwitz won the Pulitzer in 2002 for a story about a series of deaths of foster children under the care of government officials. She was part of reporting teams that won the award in 1998 and 2007. She has been with The Washington Post since 1984.