Artyom Shustov (right) was stabbed to death by his friend Nikita Rasskazov (left), in Komsomolsk-on-Amur. Picture: The Siberian Times

Nikita Rasskazov was 16 when he killed Artyom Shustov, 19, with a barbecue knife after his girlfriend told him that he had molested her at a party after she refused to have sex with him.

Olena Matsneva, 17, said Shustov and another male friend had touched her breasts and genitals, as she was held by another young woman.

This left Olena 'humiliated', but she did not report the alleged sexual assault to police.

Rasskazov said he had not intended to kill or behead his friend, but to make him apologise to his girlfriend for the sexual assault when they met on 28 October 2016.

Rasskazov was trying to 'prove his love' to Olena by showing her the severed head. Picture: The Siberian Times

The talk 'turned to quarrel and then a fight', and the 16 year old stabbed his older friend to death in a park in Komsomolsk-on-Amur in eastern Russia.

Then 'blinded by rage' he decapitated Shustov, and picked up the severed head by the hair, and put it in a plastic bag which he stashed in his backpack.

He disposed of the rest of the body in bushes and covered it with inflammable liquid. He had intended to burn it but the matches did not light properly.

Olena told Nikita that Shustov had molested her at a party after she refused to have sex with him. Picture: The Siberian Times

He hid the head overnight in his wardrobe with his bloodstained clothes.

Next day he took it to show his girlfriend, who was 'distraught' over the killing. Rasskazov was trying to 'prove his love' to Olena by showing her the severed head.

Later he threw the head into a local river in Komsomolsk-on-Amur.

Prosecutors had asked for seven and a half years jail for Rasskazov, but the term was shortened to six years ten months for murder and desecration of the body.

Dmitry Shustov, 42, said: 'Of course, I think that the sentence is unfair.' Picture: Vesti.Khabarovsk

The killer was ordered to pay 2.19 million roubles ($38,000) to Shustov's family.

But the dead man's family said no money could bring back his son and he intended to appeal the 'lenient' punishment.

Dmitry Shustov, 42, said: 'Of course, I think that the sentence is unfair. The punishment cannot be compared with human life.

16 year old stabbed his older friend to death in a park in Komsomolsk-on-Amur in eastern Russia. Picture: DVhab

'In February, Artyom would have turned 20.'

Vowing to appeal, he claimed the court was wrong to consider mitigating circumstances, namely that Rasskazov voluntary surrendered, when he did not.

The court should have seen this as murder with 'particular cruelty', saying his son was stabbed at least 15 times before his head was cut off, he said.