PEZINOK, Slovakia — Marian Kocner, the Slovak businessman accused of ordering the murder of a journalist whose reporting linked him to high-level political corruption and organized crime, arrived in the courtroom wearing a flashy navy blue suit and tie.

No stranger to the news media, he smirked at the reporters filling rows of hard wooden benches.

“I’m innocent,” Mr. Kocner said after the prosecution read the charges.

But while the swagger was still there as hearings began last month in what promises to be a monthslong trial, his hands were cuffed, his family was absent and he faced a possible lifelong prison sentence if convicted of the murder of the journalist, Jan Kuciak, and his fiancée, Martina Kusnirova, both 27, who were shot dead two years ago.

The murders shocked Slovakia and spurred its largest protests since the 1989 Velvet Revolution that paved the way for the country’s eventual independence. The outrage led to the resignation of Prime Minister Robert Fico and other top government officials, and helped a political novice with a reformist vision, Zuzana Caputova, win the presidency last year.