Mohammad Ammouri, was only a short distance from his school when he was stabbed, while Anna-Lena Svenson was only 25 metres from her apartment block on her way to her job in central Linköping where she worked for an educational company. The boy died at the scene and Mrs Svenson died from her wounds in hospital some hours later.
The murderer escaped and police silence on the case last week suggested that they were decidedly short of clues as to his identity.
But on Saturday police found blood-stained clothes hidden near the scene of the murder and concluded that the killer had seriously injured his own right hand in the attacks. The clothes, along with the so-called butterfly knife which was found shortly after the murders, have been sent for DNA testing. On Sunday the hunt focused on hospitals in the area.
The weekend also brought the police another clue: an anonymous letter, whose writer claimed to have seen the killer shortly before the murders. But according to Expressen, police would not disclose whether the letter actually contained a name or just a description of the man.
A number of other witnesses have described the man and film from CCTV cameras in the area is currently being analysed.
Another possible theory emerged over the weekend, conflicting with the earlier idea that the killer was psychologically disturbed. Expressen reported that Mohammad Ammouri’s family believed they were being “shadowed” and this led to speculation that the boy’s murder was a kidnap attempt which went horribly wrong.
But on Monday afternoon police investigators were pursuing the first idea – and, according to Aftonbladet, were confident enough to say that they think they know who the murderer is.
“We’re dealing with a lunatic,” said chief prosecutor Lennart Löthman. “This is about an attacker in a state of psychosis.”
Aftonbladet reported that police have visited Linköping psychiatric clinic twice to interview patients and pressed Löthman on when they might move in on their suspect.
“I can’t say until we’ve got the results from the technical analysis,” he said. “But we’ll arrest the man soon, this week.”
On Sunday hundreds of mourners gathered in Skärholmen School in southern Stockholm for a service for Mohammad Ammouri, while in the capital’s Sergels Torg family and friends held a demonstration.
“We invite politicians to discuss how we should fight against violence,” said Hussein Ammouri, Mohammad’s uncle. “And we in the family will get a chance to say how we feel.”