Also remanded in custody was a 16-year-old girl, who is being held on suspicions of incitement to commit murder.
The two teens can be held for two weeks as prosecutors build their case, at which point a new hearing will be held to determine whether their detention should be extended.
According to prosecutor Karolina Lindekrantz, even though both suspects are young, there is sufficient reason to keep them in custody because of the severity of the crime.
In addition, argued Lindekrantz, there is a risk that the boy could influence the investigation if he were released.
The 16-year-old boy has admitted to manslaughter, according to his attorney Claes Borgström.
However, Borgström doesn’t want his client to be remanded, arguing instead that the boy should be placed in a treatment centre in accordance with Sweden’s laws governing the care of children.
A swarm of reporters had gathered outside the chambers at Södertörn District Court where the remand hearing got underway around 2pm on Wednesday afternoon.
The 15-year-old girl was found severely injured in a wooded area in Stureby south of Stockholm and later died from her injuries.
Neither of the suspects was visibly under the influence of drugs or alcohol on the night of the murder.
Investigators are still awaiting autopsy results from the victim which will determine if she had any alcohol or drugs in her system at the time of her death.