The parents of the first Russian soldier to die in Syria are demanding a repeat autopsy, the Novaya Gazeta newspaper reported Wednesday, a day after they said they doubted the military's account that their 19-year-old son had hanged himself.

The body of Vadim Kostenko, the first Russian serviceman confirmed dead in four weeks of airstrikes in Syria, was delivered Tuesday to his parents, who said they did not believe he had killed himself.

Alexander and Svetlana Kostenko said their son had sounded cheerful over the phone as recently as Saturday, the day he died while working at an air base on the Syrian coast. Russia's Defense Ministry said he had killed himself because of problems in his personal life with an unnamed girl.

Novaya Gazeta reported Wednesday, the day that Vadim's funeral was due to take place, that his body was in a poor state. It cited the dead soldier's uncle as saying his nose, jaw and neck had been broken, that the back of his head had been smashed in, and that he had a cut extending to his belly button.

The official reason for his death was asphyxiation, the newspaper said.

Separately, the office of Russia's main military prosecutor said the same day that it was looking into Kostenko's death. It said its initial findings confirmed he had hanged himself.