Patrick J. Sloyan, a Newsday journalist whose skepticism toward official Pentagon statements led to a Pulitzer Prize-winning series on the first Gulf War, in which he revealed that many U.S. troops died by friendly fire and U.S. forces buried Iraqi troops alive in the desert, died Feb. 4 at his home in Paeonian Springs, Va. He was 82.

The cause was colon cancer, said a son, also named Patrick Sloyan.

Mr. Sloyan, who became a reporter while serving in the Army in the 1950s, spent much of his career in Washington, first with United Press International and later at the D.C. bureau of the Long Island-based Newsday.

He covered many of the most memorable stories of the 1960s and 1970s, including the civil rights movement, Vietnam War and Watergate. He was among the first reporters to highlight automobile safety concerns raised by consumer advocate Ralph Nader.

“He had an eye for newsworthy subjects that most reporters would gloss over,” Nader said Thursday in an interview. “He couldn’t stand cowardly journalists who wouldn’t ask the impertinent question.”

Mr. Sloyan was dispatched by Newsday to cover Operation Desert Storm, the short-lived conflict with Iraq known as the 1991 Gulf War. President George H.W. Bush declared a cease-fire after four days of hostilities, in what was initially seen as an overwhelming U.S. triumph.

Pentagon policies established under then-Defense Secretary Richard B. Cheney did not allow journalists to roam freely among the troops, and their reports were subject to censorship. After returning to the United States, Mr. Sloyan continued his search for answers.

He scoured military documents and interviewed hundreds of troops and their families before publishing a series of articles demonstrating that the United States’ involvement in the war was far more problematic than Pentagon had let on.

He showed that U.S. casualties from friendly fire were, in the words of military officers, “staggering” and “a disaster.”

“More than half the U.S. Army deaths and injuries during the four-day Desert Storm ground war were the result of friendly fire,” Mr. Sloyan wrote. At least 24 of the 46 U.S. troops killed during the four-day conflict, he found, died of injuries from friendly fire.

He also revealed that more than 30 U.S. tanks, armored personnel carriers and other military vehicles were destroyed by U.S. weaponry — including by uranium-tipped, armor-piercing shells not used by any other country.

“Six months after these friendly fire incidents,” Mr. Sloyan wrote, “most American families of the victims have not been officially informed of the exact cause of death or injury.”

One young widow told Mr. Sloyan that her husband’s tank was hit by three rounds from another U.S. tank, then burned for 48 hours.

“Why don’t they tell me the truth?” she said of her dealings with military officials. “One of his buddies called last week and told me exactly what happened.”

Mr. Sloyan also disclosed that the first Gulf War’s largest ground battle occurred two days after the official cease-fire.

Another of his discoveries was the gruesome manner in which many Iraqi soldiers — thousands, in his estimation — died, as they were buried in the desert by plows attached to U.S. tanks and other military vehicles. Some of the Iraqis were alive and firing their guns as they were plowed into trenches and covered with sand.

The Pentagon reluctantly admitted that the events took place. As repugnant as the incidents may have been, Mr. Sloyan noted that they occurred as acts of war and were not strictly illegal. What he objected to was concealing the truth.

“Sloyan covered the war firsthand and, in the aftermath, has doggedly pursued the innards of the conflict that he and the rest of the press corps were prevented from seeing,” wrote Newsday columnist Sydney H. Schanberg, who received a Pulitzer Prize in the 1970s for his coverage of Cambodia’s “killing fields.”

“Since the American people were asked to consent to the war, why shouldn’t they be treated as adults and told clearly about war’s bloody truths? Why did the White House and Pentagon cover up this story?”

Patrick Joseph Sloyan III was born Jan. 11, 1937, in Stamford, Conn. He moved frequently as a child, following his father’s career as an engineer. His mother was a homemaker.

While serving in the Army in the 1950s, Mr. Sloyan began working for military publications. He once wrote about an Army cook who was court-martialed for using too many potatoes. The story was promptly picked up by news services, but Mr. Sloyan was fired.

After graduating in 1960 from the University of Maryland, Mr. Sloyan worked at newspapers in Albany, N.Y., and Baltimore before going to UPI and later to Hearst newspapers’ Washington bureau. He joined Newsday in 1974.

He was based in London for five years in the 1980s and won a writing award from the American Society of Newspaper Editors for his coverage of the 1981 assassination of Egyptian President Anwar Sadat. Mr. Sloyan’s Gulf War coverage also received the prestigious George Polk Award. He retired in 2001.

In 2015, he published “The Politics of Deception: JFK’s Secret Decisions on Vietnam, Civil Rights, and Cuba,” a book debunking some of the myths surrounding President John F. Kennedy.

Basing his research on newly released White House tapes, Mr. Sloyan argued that Kennedy was “devious, ruthless . . . more pragmatic than principled” and had, among other things, orchestrated a coup in South Vietnam.

Survivors include his wife of 58 years, the former Phyllis Hampton of Paeonian Springs; three children, Nora McLaughlin of Paeonian Springs, Patrick J. Sloyan IV of Greensboro, N.C., and John Sloyan of Reno, Nev.; a sister; a brother; and 12 grandchildren. A daughter, Amy Sloyan, died in 1979.

When Mr. Sloyan was awarded the Pulitzer for international reporting in 1992, he said, “I’m delighted and honored. I want to thank everybody who made this possible, including George Bush and Dick Cheney and the rest of the government that tried to keep us from doing our job.”