Shaun D. Mullen, 72, a blogger and author whose journalism career included two decades at the Philadelphia Daily News, was found dead Thursday, Dec. 12, at his home in East Stroudsburg, Pa. He died of natural causes, relatives said.

Mr. Mullen covered the Vietnam War, the O.J. Simpson trials, the Clinton impeachment, and 12 presidential campaigns including posts on his politics blog, Kiko’s House. Mr. Mullen joked on the blog that the 2020 presidential campaign would be his “unlucky 13th.”

The day before he died, Mr. Mullen, known for a sharp, no-nonsense political voice, put up a blog post about Attorney General William Barr, headlined: “Barr Keeps Covering for Trump’s Crimes. The Time Has Come to Impeach Him.”

He also wrote regularly for another blog, The Moderate Voice.

Mr. Mullen was born in Wilmington and graduated from John Dickinson High School, where he edited the school newspaper. He attended the University of Delaware, where he was editor of the Review during the turbulent years of 1967-69. He left college three credits shy of a bachelor’s degree, his sister said.

He went to work for the Wilmington News Journal, then was drafted into the Army. Instead of being sent to Vietnam, he was assigned to Japan to work on the Pacific Stars and Stripes newspaper. After his Army service, he returned to the News Journal in 1973 as deputy news editor.

In 1981, the Daily News hired him as night city editor. Former colleagues remembered him as an editor who remained calm under pressure, with an almost Zen-like manner.

Former staff writer Gene Seymour was among Daily News reporters out until 2 or 3 in the morning amid the chaos of the May 1985 Philadelphia Police bombing of the MOVE compound on Osage Avenue that killed 11 people, including five children, and destroyed 60 homes.

When he returned to the newsroom exhausted the next day, Seymour recalled, “I remember coming back, and Shaun was in the slot, and thinking everything is going to be OK because Shaun’s in charge. He was the calm center of all that.”

Ramona Smith, a former Daily News reporter and editor, was Mr. Mullen’s assistant on the night city desk for a time.

“He could make decisions very quickly and well,” Smith said. “He was generally quick to respond and decisive. And when it came to breaking news, he had a very good instinct as to when to send the troops and when not to.”

In 1987, Mr. Mullen supervised a Daily News special section, “The Six Hundred and Thirty: Stories of Philadelphia’s Vietnam War Dead,” biographies of 630 Philadelphians who were killed or went missing during the Vietnam War. That number later was increased, according to the University of Delaware Library’s archives, where Mr. Mullen’s journalism papers can be found.

“That was his project, and it was a fabulous project,” said former Daily News and Inquirer photography editor Michael Mercanti. “It was one of the best things the Daily News ever produced, and it was all Shaun’s work. Just the effort of getting all of the photos from the Army Department was really difficult.” The project was completed in time to coincide with the city’s dedication of the Vietnam War Memorial at Penn’s Landing.

Former Daily News reporter Kitty Caparella said Mr. Mullen “was a kind, dear friend, though we’d battle over editing, but he always made things better. He brought light where there wasn’t.” As an example, she noted, Mr. Mullen’s work reported that Thomas Alva Edison High School in North Philadelphia had the largest Vietnam War death toll among graduates of any high school in the U.S.

Throughout 2000, Mr. Mullen wrote a daily column under the pen name “Millennium Man,” a fictional 120-year-old “lost soul” recounting 20th-century events.

Former Daily News photographer Susan Winters, who now lives in South Africa, said the two kept in contact even after she moved abroad.

“Shaun was a dormant volcano,” Winters wrote in an email. “Firmly grounded in his belief system, which made him powerful and demanding of respect, something he did not get as often as he should have. Silently capable of great passionate explosion.”

After leaving the Daily News in 2001, Mr. Mullen worked in the University of Delaware Library’s special collections department.

He authored two books, The Bottom of the Fox: A True Story of Love, Devotion & Cold-Blooded Murder (2010) and There’s a House in the Land: A Tale of the 1970s (2014).

Before moving to East Stroudsburg, Mr. Mullen lived for many years in Chester County.

Mr. Mullen is survived by his longtime partner, Deborah Jan Olson; a son, Cassidy; a daughter, Rory; a brother; a sister; and three grandchildren.

Funeral arrangements were incomplete.