The tension is disabling. No-one dares to speak. It's the airless interview room on the second floor of Detention Centre 45/5 in St Petersburg. A lawyer feverishly writes notes - the only sound is the scratching of his pen. Then the Russian prosecutor sucks noisily on his cigarette. This is a crucial moment for psychiatrist Dr Valery Ivanov. After two days of interrogation, he has made a breakthrough. He has convinced the shaven-headed prisoner slumped opposite him that he understands, that he can empathise even, with the crimes he has committed.

On the face of it, the conversation he has tempted the prisoner into sounds quite normal. In fact, it is anything but.

'Have you tried this one?' asks the handcuffed man, his heavy-lidded eyes suddenly animated. 'First, you fry the meat in one saucepan in a little oil; liver is best. Then, in another pot, you fry onions. Put them together with either stock or water and simmer for half an hour.' The recipe that Ilshat Kusikov, 35, is so eager to share is for human flesh. The liver he speaks of comes ripped by his own hand from a corpse that is still warm.

It is, quite literally, an interview with a vampire: one of many psychiatric investigations that will be undertaken before Kusikov faces trial later this year. Dr Ivanov, whose empathy with serial killers, after 12 years' study, has twice made him a prime suspect in multiple murders, has managed to convince Kusikov that he, too, is a cannibal and that he can be confided in. When the 50-year-old doctor talks to the cannibal, he uses the chummy diminutive of his first name: 'No, Igariok, I haven't tried that recipe. Do you think it's good?'

Author Thomas Harris knew his stuff in Silence Of The Lambs when he threw in a copy of The Joy Of Cooking among Hannibal the Cannibal's medical journals. Police searching Kusikov's St Petersburg flat last year found, among severed limbs and human organs, the old Soviet favourite Man In The Kitchen. Just as Dr Lecter experimented with recipes, Kusikov turned stray dogs and cats into burgers before upping his culinary repertoire to include his friend's liver with onions.

In the last decade, there has been an unprecedented rise in the number of serial killers in the former Soviet Union. Between 70 and 100 are currently estimated to be on the loose - and more than a dozen of these are cannibals, a group that is more prevalent in the former Soviet Union today than in any other part of the world.

The cannibals who have been captured have proved to be surprisingly matter-of-fact. Sergei Dzhumagalayev, once a paratrooper, now better known as the Kazakh Cannibal, was arrested after proudly revealing to his dinner guests the secret ingredient of his meat dumplings: a blue-eyed blonde. On Kusikov's capture, he beseeched the arresting officers to take his jars of dried ears and buckets of human bones for stock - so they wouldn't go to waste.

They are different from the run-of-the-mill serial killers in that they tend to be popular people - at least until their crimes are revealed. They are the sort of people you would go to the pub with. Dzhumagalayev was a renowned ladies' man. Kusikov was never short of a drinking partner. And even the Rostov Ripper, the schoolteacher Andrei Chikatilo, had no difficulty persuading children to come looking for mushrooms. They are mid-mannered professionals and kind-hearted grandfathers with dark secret lives.

(Cannibals have something else in common: they smell. Doctors interrogating Chikatilo - who butchered and ate parts of 52 young women, boys and girls after they agreed to go into the woods with him - spoke of the killer's pungent odour. Kusikov has the same animal smell - peculiar, say police, to psychopaths, a goaty smell that comes from an acrid sweat made by a body full of the wrong chemicals.)

Kusikov was selective in his choice of cuts. He didn't eat limbs, heads, bowels or genitals. A police video shot in his one-room apartment focused on a bag near the door containing two legs severed from below the knee and two forearms cut from the elbow. He had already dumped the head and the remaining parts of his last victim in the communal bins.

He is currently charged with the murder of three men, though police fear the real toll is much higher, and most likely includes women and perhaps even children. The heavy vinegar and onion marinade that he favoured hinders forensic identification of bodies.

The fact that he preyed on down-and-outs who would not be missed has also made the police's job harder. 'He told me he preferred the taste of men to women - though we never found any female remains,' says St Petersburg police inspector Mikhail Baluhka. 'Then he asked us if we would let him go if he let us taste a bit. He offered us some liver.'

Despite the heinous nature of his crimes, it is difficult to feel anything other than a horrified pity for Kusikov. To families living at Block 22, Ordzhonikidze Street, in a bleak St Petersburg suburb, he was an inoffensive neighbour. He was known to be a heavy drinker and sometime outpatient of a local psychiatric hospital. He had been married and had worked as a street sweeper at the local market. His only distinguishing feature was the large canvas bag he always seemed to have with him. It was found in his flat full of human bones.

'He was good with his hands,' says 69-year-old neighbour Luyba Vasilevna. 'If you ever needed help with changing a lock or a shelf, he would always muck in. He was very quiet and didn't often seem to have visitors.'

Kind and devoted to his cat Dasha - an animal that Kusikov later claimed at one stage had 'told' him to murder - he knew how to get on with people. At just less than two metres, he was taller than most Russian men, but his ready smile and comical-looking curly hair quickly put people at their ease, as did his conversation about his favourite subjects: cookery and animals.

Kusikov was on the register at the local psychiatric hospital. But when, in November 1992, neighbours made the gruesome discovery of a human torso in the basement of a local house, no-one linked it to him. ('It was an open basement - anyone could have come and dumped stuff there,' says 72-year-old Olga Petrovna, Kusikov's downstairs neighbour.)

Nor did the net start to close on Kusikov three years later, when the severed head of a vagrant, 37-year-old Misha Bochkov, was found dumped with his block's communal rubbish, or when the arms from the same body were discovered in a nearby burnt-out car.

But then, a month later, in August last year, another severed head, later identified as that of a fellow mental patient, 43-year-old Edik Vassilevski, was found by Olga Petrovna while she was walking her dogs. 'It was about 7am and already quite hot,' recalls Petrovna. 'The dogs must have smelt it. It was horrible. There were also jars with other stuff that I thought were just old bits of meat. You couldn't imagine it was human.'

Spotting Kusikov's name and that of his first and last victims on the register of the same mental hospital, the St Petersburg police finally lumbered into action. They cut off Kusikov's water and, posing as plumbers, knocked on the door of his flat. Kusikov wasn't exactly obliging - they had to batter down the door in the end - but nor was he evasive. 'He did not try to deny it,' says Baluhka. 'He was quite open when we asked about what we saw.'

Inside Kusikov's flat, its walls decorated with posters of fluffy kittens and muscle-bound martial arts film star Jean-Claude van Damme, they found Fanta bottles full of blood. An old gherkin jar was used to store pieces of dried skin and ears. On the balcony was an aluminium pot containing shashliki, Russian kebabs, skewered with onions and ready to cook. 'That was all that was left of Edik,' says Baluhka.

Back in the interview room of the crumbling, turn-of-the-century jail, cigarette smoke overpowers Kusikov's acrid smell. He gabbles away at Ivanov. He still mistakes him for a fellow cannibal: 'Come on, we understand each other. You could get me out of here. We will go off together and do things that we like to do.' With full, moist lips, he draws on a cigarette, ignoring questions from anyone except Ivanov. Ivanov smiles, anxious not to destroy Kusikov's confidence, though he knows he will never walk free.

In his confession, Kusikov has already described how he murdered his victims. 'The murders always took place on the day he received his disability pension from the hospital,' relates Baluhka. (Kusikov had been diagnosed schizophrenic in the 1980s and received a monthly payment of about R120.) 'He would ask a friend up for vodka - the first was Sasha Pichonkin. When both were very drunk, Kusikov would make a homosexual advance, which, if refused, sent him into a murderous rage.'

The fate of Pichonkin, whose name ironically means 'liver', was typical. As he slumped over the table, Kusikov struck him on the back of the head with a knife handle before slitting his throat. He then stripped himself and his victim, selected one of a dozen cleavers from a cardboard box above the bath and began dismembering the body.

In the interview room he has only a loaf of bread, brought to him by Ivanov, to gnaw on. 'You know, I always wanted to be a surgeon, but it's better to be a cannibal,' he says. 'If you are a surgeon, you have to put the body back together and you stop having any control over it. But a cannibal kills and then he can do what he wants with the body. After he kills, he owns it for ever.'

Ivanov admits he may never fully know what turned Kusikov from a young boy who dreamt of becoming a surgeon, vet or chef, to a man who derives sexual satisfaction from the smell of rotting human flesh. But he suspects a cataclysmic childhood event. Though little is known of Kusikov's early years, other than his obsession with surgery, records from Tadzhikistan, where he grew up, show that when Kusikov was 11, his father strangled his young wife, Kusikov's mother.

'The effect this had on Kusikov, we do not yet know,' says Ivanov. 'He does, however, admit that around that time he and his brother started an incestuous homosexual relationship. He also became obsessed with the human body and was able to orgasm while watching surgical operations on television hospital shows.'

Kusikov's poor school record made it impossible for him to realise his medical ambitions and, by the time his family moved to St Petersburg in the early 1970s, he was barely able to graduate from his low-grade technical college. He worked as a welder before claiming his pension. Records show that more than once he was turned down for work at a nearby morgue - he had applied to wash the corpses.

When the killings started, Kusikov's life was in turmoil: his wife, also a former patient at the mental hospital, had walked out on their two-year marriage after he attacked her with a knife; his drinking was at alcoholic level; and he was, at the very least, sexually confused. Inwardly, one can only guess at the mind of a man who by this stage was eating dogs, leaving cats rotting in his flat and drinking his own urine.

But during the interview, Kusikov has logic. He knows it's wrong to kill: but the twisted mind of a serial killer can justify his murders. He looks at Ivanov: 'You know, I am a nurse of society. I am cleaning up all the rubbish. At work, I swept streets. Now I'm just cleaning up a different kind of rubbish.' He slumps into silence, nervously playing with a packet of Marlboro.

'He has invented that excuse, used by many serial killers,' says Ivanov. He believes Kusikov is simply a sadist. 'For a sadist, the most important thing is to have complete control of their victims and they have ultimate control over them when they eat them. That is cannibalism.'

And it is on the increase throughout the former Soviet Union. Recently, a 73-year-old woman from Kaliningrad was arrested after the half-eaten body of her 82-year-old husband was found in her flat. Earlier in the year, two Ukrainian prisoners were found guilty of eating their cell mate.

'Since 1979, we've had nearly 100 people in our centre who fit the criteria of serial killer,' says Andrei Tkachenko, director of the Serbsky Psychiatric Centre in Moscow. 'In the early 1980s, we had between three and five per year. Now it's a steady 10 a year and the rate is growing.'

'In Rostov alone, we had five on the loose last year,' says Alexander Bukhanovsky, the psychiatrist whose physiological profile helped to catch Chikatilo. 'Two were caught, but three are still out there. This isn't just a sordid curiosity but probably of enormous social significance.'

Bukhanovsky believes the recent surge in serial murder and cannibalism in Russia is attributable to a wide range of factors: 'You have the collapse of the family, severe economic difficulties, a wide distribution of pornography, coupled with a lack of sex education.' Also, the cruelty of Russia's recent past, including Stalin's brutal labour camps and the widespread famine caused by collectivisation, created conditions where cannibalism certainly took place.

Another of Kusikov's neighbours, 72-year-old Lyubov Polovna, who lived through the 900-day blockade of Leningrad during World War II, hardly bats an eyelid when recounting the ghoulish activities that took place in his flat. 'Of course its terrible, but, you know, during those times, I can tell you, I was glad to eat cats and dogs. Everyone knew that some were forced to eat relatives who had died. That, or die themselves.'

The size of the country and police incompetence work to help the Russian serial killer. Sergei Rakhovsky killed more than 20 people within Moscow's city limits in the early 1990s before police suspected the crimes were the work of one man. Andrei Chikatilo was released to kill again, despite being caught near the body of a butchered girl and carrying a briefcase containing a bloodied knife.

But now it's the end of the interview with a vampire. One o'clock and Kusikov doesn't want to miss his lunch. He eats well and, say warders, enjoys his meals. As he rises, he nods at Ivanov and jokes: 'Hey, I like the look of that lawyer: he's nice. Good strong body. What do you think?'

Kuzikov, Ilshat

SEX: M RACE: W TYPE: T MOTIVE: PC-nonspecific

MO: Killed/cannibalized male acquaintances

DISPOSITION: Ruled insane, 1997

Ilshat Kuzikov

Ilshat Kuzikov