Marinova’s body was found in a park in the Bulgarian border town of Ruse on Saturday

A man has been arrested over the rape and murder of the journalist Victoria Marinova, Bulgarian authorities have said, adding that they do not believe the attack was linked to Marinova’s work.

The body of Marinova, 30, was found by a passerby on Saturday, after she had gone running along the Danube in Ruse, Bulgaria’s fifth biggest city. She presented a programme on TVN, a local channel.

The man, named as 21-year-old Bulgarian citizen Severin Krasimirov, was detained by German police near Hamburg on Tuesday, at the request of Bulgarian authorities.

“We have enough proof linking this person to the scene of the crime,” said Bulgaria’s interior minister, Mladen Marinov, on Wednesday. Krasimirov, a resident of Ruse, has a criminal record for scrap metal theft, he said. The minister said investigators had spoken to the journalist’s family and friends and added: “There is no apparent link to her work.”

The chief prosecutor, Sotir Tsatsarov, said Krasimirov was already wanted by police over another rape and murder, and added that he did not believe the killing of Marinova was connected to her work, suggesting it was a “spontaneous” attack.

The attack marked the third death of a journalist in an EU country in the space of a year, prompting fears Marinova could have been targeted for her work, especially given that her final broadcast involved an interview with two investigative journalists who were looking into high-level corruption.

On Wednesday morning, however, Bulgaria’s prime minister, Boyko Borisov, launched an attack on journalists and his political opponents, criticising them for speculating that Marinova had been killed because of her journalism.

“I read monstrous things about Bulgaria in the past three days and nothing was true,” he said. “We, as a country, did not deserve to be smeared like this.”

Many European figures tweeted their concern after the killing, including the European commission’s vice-president, Frans Timmermans. He wrote on Twitter: “Shocked by the horrendous murder of Victoria Marinova. Again a courageous journalist falls in the fight for truth and against corruption.”

On Wednesday, Antonio Tajani, the rightwing Italian president of the European parliament, congratulated Bulgarian authorities on Twitter, commending the arrest and stating without evidence that the motive for her murder “was not related to her work as a journalist”.

Borisov lashed out at political opponents for “sending emails to Brussels and the United States, as if this is not something that happens in other countries and is an isolated case”.

The prime minister later invited foreign ambassadors stationed in Sofia to hear a report on the investigation so far. He told the reporters present at the press conference: “You have freedom to write, to talk, to broadcast on every subject.”

Bulgaria has been ranked the 111th country in the world when it comes to press freedom, lower than any other EU state.

Some Bulgarian journalists were less than convinced that the killing was pure coincidence and criticised authorities for appearing to discount the possibility of a contract killing from the outset.

‘The horror we live in’: journalist's murder shocks Bulgaria Read more

“Viktoria Marinova was not a professional investigator but she dared to speak about this and give others the possibility to discuss it,” said Atanas Chobanov of the investigative organisation Bivol, whose journalists were interviewed by Marinova in her final broadcast. He said the portal had received “credible threats” over the report.

However, many of Marinova’s friends and colleagues have also played down the possibility that she could have been targeted for her work. Her ex-husband Svilen Maksimov, the director of TVN, told Bulgaria’s Nova TV that “all evidence points at absurd, awful coincidence”.