The crime novel Vetrarborgin (2005), translated to English by Bernard Scudder and Victoria Cribb.
From Arctic Chill:
Erlendur's mobile rang incessantly. Sigurdur Óli gave him a report about his meeting with the principal and said he was on his way to meet the boy's teacher and another member of staff who had spoken out against immigration. Elínborg called to tell him what a witness who lived on the same staircase as Sunee thought she had seen the elder brother earlier that day. The head of forensics quoted the pathologist as saying that the child had been stabbed once, presumably with a fairly sharp instrument, probably a knife.
'What kind of knife?' Erlendur asked.
'The blade would have been quite broad and even thick, but particularly sharp,' the head of forensics said. 'The stabbing need not have required much effort. The boy could have been lying on the ground when he was stabbed. His anorak is dirty on the back and torn too. It looks fairly new, so he may have been involved in a fight. He would have tried to defend himself, as is only to be expected, but the only wound is from the knife, which the pathologist said penetrated his liver. He died from loss of blood.'
'You mean that it didn't take much force for the knife to go in that deep?'
'Even a child or a young person could have done it, for instance? Someone of his own age?'
'It's difficult to say. But it looks as if it was inflicted by a very sharp instrument.'
'And the time of death?'
'Judging from the temperature, he would have died about an hour before he was found. You can discuss that with the pathologist.'
'He seems to have been coming straight home from school.'
'It looks that way.'