UPDATE 1-EU calls for fast inquiry into killing of Bulgarian journalist

The European Commission urged Bulgaria on Monday to conduct a rapid investigation into the killing of journalist Viktoria Marinova as mourners planned vigils near her hometown.

Prosecutors said the 30-year-old had been raped, beaten and suffocated. Marinova's body was found in a park near the Danube river in Ruse on Saturday.

"There is no democracy without a free press ... We expect a swift and thorough investigation to bring those responsible to justice," the European Commission, the European Union's executive said in a tweet.

Bulgaria ranked 111 out of 180 countries in the Reporters Without Borders world press freedom index this year, lower than any other EU member.

On her last aired TV show, as an anchor, on Sept. 30, Marinova introduced two journalists who were investigating alleged corruption involving EU funds. She said the regional current affairs show, "Detector", would do similar investigations.

The European anti-fraud office OLAF declined to comment on the killing. But its press office said it was "aware of allegations concerning possible misuse of EU funds in Bulgaria that have been brought to light by journalists in recent weeks".

That appearance was her first time anchoring the show on Ruse-based TV station TVN - a popular channel in northeastern Bulgaria. Previously, she was best known for presenting a regional lifestyle show and was not a household name nationally.

Interior Minister Mladen Marinov said that there was no evidence to suggest a link to Marinova's work as a journalist so far - something echoed by police and prosecutors.

"We are working on all possible motives and we do not exclude any," Marinov told reporters on Monday in Ruse, Bulgaria's main river port.

He said no match had been found for DNA sample collected so far from the crime scene, which was close to a psychiatric clinic.

Police and prosecutors said they were working on three possible motives - whether Marinova was a victim of a random attack by a person with a mental disorder, a planned attack or whether the crime was linked to her personal life.

"We do not exclude that it was a random attack, we do not exclude that it was a premeditated attempt on her life," Chief Prosecutor Sotir Tsatsarov told reporters in Ruse.

Marinova would be the third journalist murdered in the European Union over the past 12 months.

Daphne Caruana Galizia, Malta's best-known investigative reporter, was killed when a bomb blew up her car in October last year and Slovak journalist Jan Kuciak was shot dead in February.

Vigils for Marinova, mother of a seven-year-old daughter, were planned in Ruse and the northern cities of Vidin and Pleven, as well as the capital Sofia.

The TVN channel expressed shock over the killing of its colleague and board member but declined to comment further, saying it would give investigators time to do their job first. The channel was due to air a tribute to her later on Monday.

Reporters Without Borders said other TVN journalists should get police protection during the investigation. The Committee to Protect Journalists said it was "shocked by the barbaric murder".

(With inputs from agencies.)