The 17-year-old was at home with his mother and girlfriend last Wednesday evening when the phone rang. A friend had called the boy for help in a fight at Linnéskolan, a school nearby.
"He said he would be back within an hour," the boy's mother told newspaper Expressen on Tuesday.
Instead she received a call from her son's friends a few hours later - informing her that the boy's throat had been slit with a broken bottle.
Over the next few hours police conducted interrogations with a dozen or so youths who had been at the scene - and the next morning they arrested a 16-year-old acquaintance of the murdered boy.
On Tuesday, a 14-year-old boy was apprehended as an accomplice to murder. While he didn't slit the 17-year-old's throat - he is suspected of handing his friend the jagged-edged bottle which became a murder weapon.
With regard to his age, the youngest boy is now in custody of social services.
Police said that the group of boys had known each other for several years. The 16-year-old suspected of murder was reportedly upset with the 17-year-old for his involvement in a robbery.
The 16-year-old was also previously known to police for charges of assault and violation of knife laws.
Flowers and candles have been placed at the scene of the murder as the community mourns.