Tony Horwitz, a Pulitzer Prize-winning reporter and best-selling author known for embedding himself in the worlds he wrote about, whether joining a slaughterhouse assembly line or an army of Confederate battlefield re-enactors, died on Monday in Washington. He was 60.

His wife, Geraldine Brooks, a Pulitzer Prize-winning novelist, said he had collapsed while walking in Chevy Chase, Md., and was declared dead at George Washington University Hospital.

The cause had not been immediately determined, but on Friday, the family said an autopsy had determined that it was “sudden cardiac arrest.”

Mr. Horwitz was on the staff of The Wall Street Journal when he won the 1995 Pulitzer for national reporting for his vivid accounts of grim working conditions in low-wage jobs, including those at garbage recycling and poultry processing plants. He later wrote for The New Yorker on the Middle East before amplifying his brand of participatory journalism in nonfiction books.