Freedom isn’t always what it’s cracked up to be, especially if you’re young. Getting away from the occasionally suffocating gaze of family or school may feel like a thrilling liberation but it has its attendant dangers, as horribly illustrated by the case of Meredith Kercher and her flatmate Amanda Knox. Kercher, 21, was living in Perugia as part of her European studies degree at Leeds University. She was found, partially clothed and with her throat cut. Her flatmate Knox, 20, an American student, is a suspect, as are Knox’s boyfriend, Raffaele Sollecito, 24, and Patrick Diya Lumumba, 37, a Congolese bar owner for whom Knox sometimes handed out flyers.

The three are being held on suspicion of killing Kercher after she apparently refused to have sex with them. Under Italian law, they can be held for up to a year before charges are brought.

Lumumba, who has a wife and two children, says he can prove his innocence. Sollecito says his memory is blurry because he had been smoking marijuana. Knox has, according to Italian police, said Lumumba “wanted” Kercher, that he went into her room and that she (Knox) tried to ignore the subsequent screaming by covering her ears.

I find the hear-no-evil, ear-covering part particularly disturbing, partly because it seems to be so much about the invincibility of youth, or rather the feeling that youth makes you invincible, especially if you are free to do as you please for the first time – especially if you feel like doing something slightly baroque and especially if that baroque thing involves sex.

Being away from home and in a university town, it’s easy to feel that usual rules don’t apply and that warning signals can be ignored because it all seems so benign: everyone is friendly; you’re naive enough to find a certain glamour in handing out leaflets advertising a popular bar and naive enough either not to see that your youthful prettiness is being used as bait (or, more naively still, to see it clearly but feel ironic and postfeminist about it); and you feel safe.

What is so uncomfortable about this story is how quickly that familiar-seeming situation spiralled out of control. Kercher went back to her sweet little house with her friend and a couple of blokes they both knew, and ended up murdered.

I was at boarding school with a girl who is serving a 90-year sentence at a prison in Virginia for being an accessory to the murder of her parents in 1985, when she was 20. She is called Elizabeth Haysom and when she went to jail, having pleaded guilty to conspiracy to kill her parents in 1987, the Berlin Wall was still up and the internet didn’t exist. Her then boyfriend Jens Soering, the son of a German diplomat, was convicted on two counts of first-degree murder and is serving two life sentences.

I never met Soering, but Elizabeth was perfectly charming and only minutely odd, in that self-consciously “rebellious” teenage way. We used to smoke illicit cigarettes together while listening to David Bowie. She was intelligent and funny and very striking physically. This was in the first year of the sixth form; I got expelled shortly afterwards.

Elizabeth then defrauded half a dozen girls of their chequebooks and got kicked out, too. I went to a crammer and did my A-levels and Oxbridge, and she encouraged her boyfriend to murder her parents and he did. Just like that. Her contemporaries have known births, deaths, marriages, divorces, jobs, but Elizabeth has spent the past 20 years locked up.

I think about her often – there was a little group of us at school who thought we were terribly naughty and daring because we smoked the odd joint or snuck in the odd drink, but nobody would in a million years have imagined that one of us would go on to serve 90 years for murder.

I remember being at a drinks party in Cambridge a few years later, sipping Pimm’s on the Backs in the sunshine, when another old schoolfriend came running up with the Daily Mail: there on the front page was Elizabeth’s police mugshot and a picture of school and a screaming headline about privilege and depravity.

Soering has since said that he confessed only to spare Elizabeth the death penalty (the trial took place in Virginia, where she and Soering had been at university until they did a runner after the murder – they were arrested in England on cheque fraud charges).

He has said: “I see myself as the victim of a young woman who was mentally ill.”

Knox’s boyfriend of two months may come up with a similar line. And Knox’s friends may express similar incredulity at the thought that their mate could be involved in anything as gruesome as the murder of a young girl.

On the Seattle campus of the University of Washington, where Knox was studying German, Italian and creative writing, one of them said last week: “She has got a huge number of friends over here who are all completely shocked and baffled. This doesn’t even come close to the character of Amanda. She’s a person who loves others, she doesn’t have a mean streak in her whatsoever.”

The boy who took her to the school prom said: “The girl I knew and was friends with was a sweet, innocent girl who loved playing soccer and singing in choir. But people change, especially once they leave a rather sheltered preparatory school and enter university.”

I suspect Knox, too, was part of a harmless little gang that considered itself cool and edgy. On her MySpace page, she referred to herself as “Foxy Knoxy” and posted a couple of stories, or perhaps fantasies, about drugging and raping a woman and photographing a woman in bed without her knowledge. That may or may not be significant – she is a creative writing student, after all – but it was certainly unwise and naively provocative.

She must have felt invincible: pretty, young, bright and free to do as she pleased in an exciting new country. It will be some time before we know what happened to Kercher that night, but we do know this: when you’re young, sometimes there is the thinnest line between fun and horror, between sex and violence, between an argument and someone getting out a knife.

Invincibility – that all-conquering feeling – is thrilling and possibly the best part of youth, but it’s also an illusion. Just ask my sometime schoolfriend, who seemed neither mad nor bad and who has spent more than half her life behind bars because one night, aged 20, she thought the unthinkable and acted on it.

india.knight@sunday-times.co.uk

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