The squalid, lonely death of Ivan Kanev

The final breath rattled through Ivan Kanev's sallow, spent torso. For months he had injected eye drops called tropicamide – used medically to dilate pupils – directly into the femoral artery of his groin. The drug is known as "seven-monther" – the amount of time it takes to kill. His body was found by his father in his Moscow apartment. The 25-year-old had died alone.

Ivan's father Sergei sits in a greasy chicken shop in the Moscow suburb of Lubna. Extending a nicotine-stained finger, he prods a black Dictaphone and says: "He was this colour and bigger than me." Sergei is a huge, hulking man, with broad shoulders, but Ivan was slight, pale and blond. It is unclear whether the bloating happened before or after his death.

As crime correspondent for Russian newspaper Novaya Gazeta, Sergei has long contemplated his own death. The paper is known for its fearless reporting and the murder of its journalists, including Anna Politkovskaya, chronicler of the Chechen conflict. There have been several attempts on Sergei's life – a thug once lay in wait to strangle him with a wire in his apartment stairwell. These days, he keeps a video camera rolling in his bag everywhere he goes so that any would-be assassin may be captured.

A recent article in Novaya Gazeta, written by one of Sergei's colleagues, accused the Russian government of allowing drugs companies to profit from medicine addicts.

Sergei says street pushers, chemists, the police, pharmaceutical companies and the government are all implicated in a vast protection racket. He refers to those involved as "Chekists", alluding to the Cheka, the first Soviet security agency.

Russia has the second highest number of opiate users in the world after China, according to the United Nations Office on Drugs and Crime (UNODC). As the government takes measures to stem the flow of heroin seeping into the country from Afghanistan, leading to a smaller, more expensive supply, cheap over-the-counter drugs have become a popular substitute.

Krokodil – its medical name is desomorphine – is a favourite. Synthesised from codeine, it slowly rots the body over a period of around two years. Nikolai Kartashov, the deputy head of the Federal Drugs Control Service, told the Russian press that in 2010 krokodil accounted for between 60 and 70 per cent of drug busts. The same agency reports 40,000 drug-related deaths each year.

Various estimates put the number of krokodil users at between 100,000 and a million, but as it is a cheap substitute drug and users rarely visit rehab centres, the actual number is difficult to calculate. "We have no estimates on the misuse of prescription drugs in Russia," says Angela Me, the chief of statistics and surveys at UNODC. The government can claim huge successes in its "war on drugs" after major heroin busts, but chemists are filling the void. Meanwhile, young people across Russia like Ivan Kanev are trapped in an inevitable, slow suicide.

In the months before his death, Ivan emitted a green hue, his head perpetually tilted back, his eyes were vacant, and he appeared ghoulish. Every three hours, day and night, he rushed to a chemist called "Kind Mother". The eyedrops cost 400 roubles (£2) with a prescription, but at Kind Mother they are available to anyone for an extra 50 or 100 roubles. Sergei says there are 40 such pharmacies in Moscow. Kind Mother is open until midnight. After that a man stands on the street pushing prescription narcotics.

Ivan had a two-year respite from his medical drugs binge while imprisoned for stealing mobile phones. Inside he was only able to obtain heroin, sold to inmates by warders. His addiction became less toxic, he went to the gym and wrote a letter to his father promising to turn his life around.

While Ivan was in prison, Sergei watched his son's childhood friends degenerate from addiction. According to Avert, the international HIV/Aids charity, one-fifth of injecting drug users contract HIV, and the number living with the disease in Russia is just under a million. Ivan's best friend, nicknamed Pushkin because of his big, curly hair, visited Sergei while Ivan was inside. He had Aids, was hooked on over-the-counter drugs, in chronic pain and homeless. Using the familiar and deferential word "uncle", he begged Sergei to help him hang himself. Sergei refused, and a month later, he says, Pushkin died a savagely painful death.

Ivan was out of prison for only a week when the lure of prescription medicines trapped him again. He became vacant, gaunt and pale, as if death had already begun to claim him. He stole from his father and erupted into fits of anger, smashing family photographs. There are now few images left of Ivan apart from those of his corpse.

While Sergei was out of town for work, Ivan's heart stopped and he had to be revived by friends. Sergei told him it was his first warning that he was going to die. Ivan realised he had been taking the "seven-monther" for five months. That meant he had only two months left. He decided to kick the habit. He cleaned his flat, applied for jobs and took exercise. His cheeks ached from smiling for the first time in months.

It lasted a week. The final chapter of his life was the most painful for his father to watch. Sergei offered the police money to put Ivan back in prison and they agreed to concoct a burglary for 5,000 roubles. But Sergei backed down, knowing burglary carried a hefty sentence. "I wanted him to go to prison for his actual crime – taking drugs," he says.

On a bleak, brutally cold morning in March, Sergei got a call at work from his mother. A framed photograph of Ivan had come crashing to the floor of her apartment – she took it as a sign. Sergei rushed to Ivan's flat. A note on the door read, "Ring loudly because I'm sleeping". Sergei rang, knocked, then bashed the door. No one stirred and the door was jammed shut. He called the police, who broke it down.

Ivan's head, neck and shoulders were black and had swollen to double their size. "I didn't recognise him apart from the pin pricks in his skin," Sergei said. The crime correspondent in him took over. He took his camera out of his bag and committed it all to film.

He shows stills from the film to anyone willing to look. Ivan's torso was charred from the chest up; he lay half sprawled, half in the foetal position, on his bedspread, blackened pools of blood next to him, his mobile phone at his side. His eyes squeezed shut, his mouth seemingly mid-howl, he looks as though an explosive had gone off inside him. "He died like a match that went up in flames," Sergei said.

The police told Sergei they pick up a couple of overdose corpses in Moscow each week. He met parents at the morgue who were burying their second child lost to drugs. Sergei got rid of the family-owned apartment where Ivan had stayed and where the acrid scent of drugs cooked by his friends clung to the walls.

Lubna's graveyard seems disproportionately large for the suburb's population. Ivan is buried next to Sergei's wife, in a plot he had reserved for himself, never expecting to outlive his son. Sergei's wife died 10 years ago and they had only two children. None of Ivan's friends made it to his funeral – they were all dead or in prison. It was attended by a priest, Sergei and his daughter Katia, 22.

A month after Ivan's death Katia died too. She was Sergei's great hope – clean-living and ambitious, she had never touched drugs. But in the dreary Moscow suburb, having friends who are addicts was unavoidable. Her ex-boyfriend, Murtaza Tsabutashvili, is on trial charged with causing her death. He hit Katia over the head while intoxicated. Sergei buried his daughter on his son's 26th birthday.