Rupert Cornwell, an award-winning British journalist who covered financial scandals at the Vatican, the fall of the Soviet Union and the 9/11 terrorist attacks on the United States and who was the half brother of renowned spy novelist John le Carré, died March 31 at a Washington hospital. He was 71.

The cause was colon cancer, said his wife, Susan Cornwell, a journalist with the Reuters news agency.

Mr. Cornwell began his career in Europe with the Financial Times and then joined the London-based Independent newspaper at its founding in 1986 as its Moscow correspondent.

“It was an exciting and hopeful time,” Mr. Cornwell wrote March 2 in one of his final columns for the Independent. “The young and charismatic Mikhail Gorbachev had become leader two years before, with the explicit mission of revitalising the country after a succession of geriatric leaders and the ‘age of stagnation’ over which they presided.”

Instead of a revival of the Soviet Union, Mr. Cornwell found himself chronicling its collapse, as voices for democratic changes began to be heard. His coverage won him Britain’s Foreign Correspondent of the Year award in 1989.

Mr. Cornwell’s journalistic approach, combining deeply sourced reporting with a confident analytical voice, helped define the tone of the fledgling Independent. (Since 2016, it has been published only in an online format.)

“Rupert understood in real time the meaning of the events he was covering,” Andreas Whittam Smith, the paper’s founding editor, said in a statement released by the Independent. “He knew the relevant history so he could provide illuminating context. And he wrote an impeccable English prose.”

In 1991, Mr. Cornwell came to Washington for the first of two stints for the Independent. After four years in London from 1997 to 2001, he returned to Washington, where he spent the rest of his career.

On Sept. 11, 2001, when terrorists flew hijacked jetliners into the Pentagon and New York’s World Trade Center, Mr. Cornwell worked at breakneck speed to compose a 2,200-word story summarizing the attack and its potential reverberations in the future.

“You struggle for historical comparison,” he wrote. “The closest surely, in the American experience, was Pearl Harbor in 1941, another sneak attack that sent thousands to their death, and briefly overwhelmed those who had to cope with it. But Pearl Harbor happened on a remote Pacific island, not at the very nerve centres of US government and business. And just like the Japanese attack on Hawaii, this was an act of war — but a war conducted by unseen assassins, who have inflicted a shattering blow.”

Earlier in his career, when Mr. Cornwell was based in Rome for the Financial Times, he happened on a case of international intrigue that could have been taken from the pages of one of his half brother’s novels. In 1982, the body of Italy’s most powerful private banker, Roberto Calvi, was found hanging from London’s Blackfriars Bridge.

In “God’s Banker,” a book first published in 1983, Mr. Cornwell explored the financial scandal surrounding Calvi’s bank, which had deep links to the Vatican and Italian political figures and was billions of dollars in debt.

Among other details, Mr. Cornwell suggested that Calvi may have been murdered, possibly in a ritual fashion. The banker belonged to a secretive Masonic lodge whose members called themselves frati neri, or black friars.

“Were there not ‘masonic’ trimmings to his death — the stones in the pockets, the choice of the bridge of Blackfriars,” Mr. Cornwell wrote in his book, “the washing of Mr. Calvi’s feet by the river tide?”

Calvi’s death was initially ruled a suicide, but in 2005 — 23 years after he died — five people were accused of killing him and put on trial. All were acquitted. The case remains unsolved.

Rupert Howard Cornwell was born Feb. 22, 1946, in London. His father, Ronnie Cornwell, was a charming con man who had been imprisoned for embezzlement.

“He saw no paradox between being on the wanted list for fraud and sporting a gray topper in the owners’ enclosure at Ascot,” his son David Cornwell, better known as John le Carré, wrote in a 2016 memoir. “A reception at Claridge’s to celebrate his second marriage was interrupted while he persuaded two Scotland Yard detectives to put off arresting him until the party was over — and meanwhile, come in and join the fun, which they duly did.”

Rupert Cornwell, nearly 15 years younger than David Cornwell, was from a later marriage that ended in divorce. His mother worked for the BBC.

Mr. Cornwell graduated in 1968 from the University of Oxford, where he studied modern Greek. He worked for Reuters for a few years before joining the Financial Times, which assigned him to bureaus in Paris, Rome and Bonn, then the capital of West Germany. He became proficient in multiple languages, including Greek, German, French, Italian and Russian.

His first marriage, to Angela Doria, ended in divorce. Survivors include his wife of 29 years, the former Susan Smith, of Washington; a son from his first marriage, Sean Cornwell of London; a son from his second marriage, Stas Cornwell of Alexandria, Va.; a sister, actress Charlotte Cornwell of Devonshire, England; two half brothers, David Cornwell (le ­Carré) of London and Cornwall, England, and Tony Cornwell, a retired advertising executive, of Seattle; and two granddaughters.

Mr. Cornwell continued to write for the Independent until shortly before his death. His columns on the political rise of President Trump had a particularly sharp edge.

“Theodore Roosevelt was right when he pointed to the ‘bully pulpit’ power of the office,” Mr. Cornwell wrote in November. “The soon to be 45th president most certainly is a bully. But for the pulpit part to work, you need a clear majority of the country behind you. Which, right now at least, is manifestly not the case with Donald Trump.”