Anna Leontyeva, the dead mother of a 5-year-old boy whose body was found in a suitcase, was in love with a young man from Turkey, suspected by Bulgarian police of having murdered both, told a Russian daily.

In an interview with Komsomolskaya Pravda, German Kostin, 50, denied any involvement in the developments, sarcastically describing himself as "the monster who is being sought as a suspect".

Kostin, who lives in Cyprus with his wife and two daughters, said the last time he saw Anna was in Sofia in February, as she was getting into a car with a Turkish license plate with her son, Nikita.

In the words of Kostin, she was accompanied by a man "aged about 35".

Kostin also explained he knew Anna because she had lived next door to him for some time in Cyprus.

He asserted he would come to Bulgaria to give testimony in April.

Nikita's murder shocked many people in Bulgaria after two photographers stumbled upon a suitcase containing his lifeless body while taking pictures near the village of Pasarel, kilometers away from the capital Sofia.

The news sparked some initial confusion, with police being unable to establish his identity for some time.

Preliminary information of investigators suggests the boy was killed a few weeks after his mother.

Russia pledged earlier this week to provide assistance to Bulgarian authorities.

Anna and Nikita rented an apartment in the Black Sea resort of Primorsko, where Anna was found dead on March 2.   

Reports of Komsolmolskaya Pravda suggest she left the city of Perm, Russia, three years ago. By that time she worked at the Perm Governor's office at the human resources department. She allegedly moved from Russia to "give [her] son European education", as the paper quotes her as "telling everybody".

She came to Bulgaria three months before the murder, having lived in Cyprus immediately after leaving Russia.