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

Daphne Caruana Galizia, 53, had just driven away from her home in Mosta, a large town on Malta’s main island, when the bomb went off, sending the vehicle’s wreckage spiralling over a wall and into a field, Prime Minister Joseph Muscat said.

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

One of the topics the veteran reporter examined was what the documents from the 2016 leak said about Malta. She wrote that Muscat’s wife, the country’s energy minister and the government’s chief-of-staff had offshore holdings in Panama to receive money from Azerbaijan.

Muscat and his wife, Michelle, denied they had companies in Panama.

Caruana Galizia filed a police report two weeks ago saying she was receiving threats, law enforcement officials told Malta news outlets on Monday.

The slain journalist had been a regular columnist for The Malta Independent, writing twice weekly for the newspaper since 1996. She also wrote a blog called “Running Commentary,” which was followed by in Malta.

A half hour before she was killed, she posted to her web site an item about a libel claim the prime minister’s chief of staff had brought against a former opposition over comments the latter made about corruption.

Caruana Galizia herself had been sued for libel over articles she wrote for her blog. Opposition leader Adrian Delia sued her over a series of stories linking him to a prostitution racket in London. Economy Minister Chris Cardona claimed libel when she wrote that he visited a brothel while in Germany on government business.

Monday evening’s Parliament session was scrapped, except for briefings about the bombing given by Muscat and Delia, who called the reporter’s slaying a “political murder.”

Muscat said he has asked the US government and the FBI for help investigating the car bombing.

Caruana Galizia is survived by her husband and three sons. One son, Matthew, was on the International Consortium of Investigative Journalists team that won the Pulitzer Prize for its work on the Panama Papers scandal.

The leak exposed the identities of rich and powerful people around the world who allegedly had offshore holdings in Panama.

Caruana Galizia’s family has asked the Courts of Malta to have the magistrate assigned to conduct the inquiry into the journalist’s death replaced.