A total of seventeen people have been interrogated in the murder case of a young woman in Sofia's central park Borisova Gradina.

The information was reported by Darik radio Friday, citing their own, undisclosed police sources, who have further said the girl had elevated levels of alcohol in her blood.

The autopsy showed that Yana Krasteva, 28, had been strangled. The police are working on a lead the woman was killed by someone she knew. The coroner's report says she had sexual contact shortly before her death, but it is unclear if this has been rape. Previous reports stated the woman has been raped.

Another version is that Krasteva has been killed by a passerby. The park has been crowded on the night of the murder – about 5 000 were there on July 9 for a concert from the program of the Sofia Rocks festival.

There are ongoing blood tests to establish if the woman had taken any illegal drugs. The investigation continues, according to the Darik source.

Krasteva was born in the village of Harlets, near the town of Kozloduy on the Danube River. She had been living in Sofia for years, and was selling toys in a mall in the city. She applied for college shortly before the murder.

Meanwhile, discontent over the lack of response from the Bulgarian Interior Ministry and Interior Minister to Krasteva's in murder caused civil society groups and concerned citizens to launch a protest campaign, including a Facebook group which gathered together over 4 000 supporters in just one day.