Bulgarian television reporter Viktoria Marinova has become the third journalist to be murdered in the European Union in the last year and the fourth since the start of 2017.

The 30-year-old’s body was found dumped near the Danube River in the town of Ruse, northern Bulgaria, on Saturday. Police said she had been beaten, raped and strangled.

It is not known if Marinova’s murder is linked to her journalism work. Investigators are still trying to trace potential witnesses and establish a motive for her killing. However, Bulgarian media reported that Marinova recently interviewed Romanian journalists who were investigating politicians and businessmen for alleged corruption of EU funds.

“It is about rape and murder,” Interior Minister Mladen Marinov said, apparently concluding there was no evidence to suggest the killing was linked to Marinova’s work.

Marinova worked for a small local TV station called TVN where she presented two investigative programs. The Organization for Security and Cooperation in Europe, an intergovernmental organization, called for a “thorough investigation” of her rape and murder, noting “a trend of increased attacks against female journalists.”

Maltese investigative journalist Daphne Caruana Galizia was killed in a car bomb in October. She had worked on the so-called Panama Papers, leaked documents that revealed financial information about the offshore accounts of high-profile officials. Slovakian investigative journalist Jan Kuciak and his girlfriend were shot to death in February. Kuciak was investigating tax fraud. Swedish freelance journalist Kim Wall was murdered in a gruesome case in Denmark last year by Danish inventor Peter Madsen. Wall was killed and mutilated after boarding Madsen’s submarine to do an interview.

Frans Timmermans, vice president of the EU’s executive branch, tweeted: “Again a courageous journalist falls in the fight for truth and against corruption. Those responsible should be brought to justice immediately by the Bulgarian authorities.”

Bulgaria ranked 111 out of 180 countries in the Reporters Without Borders world press freedom index this year. That’s lower than any other member of the EU. Worldwide, at least 48 journalists have been killed doing their work in 2018, according to the Committee to Protect Journalists, an organization that promotes press freedom.

Turkey’s President Recep Tayyip Erdogan told reporters on Sunday he is personally looking into reports that Jamal Khashoggi, a Saudi Arabian journalist for the Washington Post, may have been killed while visiting the Saudi consulate in Istanbul last week. Khashoggi’s wife reported him missing after he failed to return from an appointment there. Khashoggi is a critic of Saudi Crown Prince Mohammed bin Salman.