VALLETTA, Malta (AP) — A Maltese investigative journalist who exposed her island nation’s links to offshore tax havens through the leaked Panama Papers was killed Monday when a bomb exploded in her car, Malta’s Prime Minister Joseph Muscat said.

Daphne Caruana Galizia, 53, had just driven away from her home in Mosta, a town outside Malta’s capital of Valletta, when the bomb went off, sending the vehicle’s wreckage spiraling over a wall and into a field.

Muscat says Caruana Galizia’s death resulted from a “barbaric attack” that also amounted to an assault on freedom of expression. He described her as “was one of my harshest critics, on a political and personal level,” as he denounced her slaying.

Politico named Caruana Galizia as one of 28 Europeans who are “shaping, shaking and stirring” Europe. She revealed that Muscat’s wife, Michelle, as well as Muscat’s energy minister and the government’s chief-of-staff, held companies in Panama by looking into the 2016 document leak. Muscat and his wife deny they held such companies.

Opposition leader Adrian Delia called the killing a “political murder.”

Caruana Galizia had been sued for libel because of various articles she wrote on her blog “Running Commentary,” and she had filed a report with the police two weeks ago that she was receiving threats.

Monday evening’s Parliament session was scrapped, except for briefings about the bombing scheduled to be given by Muscat and Delia, the opposition leader.

In June, Muscat was sworn in for a second term as prime minister following snap elections he had called to reinforce his government as the Panama Papers’ leak indicated his wife owned an offshore company. The couple denies wrongdoing.

The leak exposed the identities of the rich and powerful around the world with offshore holdings in Panama.