He had been reported missing earlier in the day after disappearing from a residential area playground.
The boy had left his home in Ljungby on Sunday afternoon to go play in a nearby playground.
According to the local Smålands Posten newspaper, he went missing after having an argument with older siblings, but no one seemed to notice he was gone.
Around 10pm, the boy’s lifeless body was found just a few hundred metres from his home, in a small wooded area adjacent to the playground, five hours after he had last been seen.
At first police downplayed the possibility of foul play, but on Monday morning they said that they continued to explore whether or not a crime took place.
“It can’t be ruled out, but it’s too early to say anything definitive about it,” police spokesperson Reinhold Liljedahl told several media outlets
He told Sveriges Radio (SR) that the boy’s body was found near a trail in the woods, not far from the playground.
As police have yet to rule out that the boy was killed, a preliminary criminal investigation into murder has begun, according to local media.
“Our forensic officers have investigated the location where the boy was found and they can’t say for sure whether this is an accident or if a crime has been committed. This means that we routinely instigate a preliminary investigation into a possible murder, pending results from the autopsy,” said Robert Loeffel, head of informations at the Kronoberg Police.
Police had been notified of the boy’s disappearance at 7.30pm, prompting a massive search that included sniffer dogs and six patrol teams.
Several volunteers also participated in the search for the missing 4-year-old.
“The siblings and parents looked themselves at first, but when they couldn’t find him they called police,” duty officer Christer Karlsson of the local police told the newspaper.
In the initial stages of the search, police looked in stairwells, sheds, and cellars, guessing that the boy may have sought shelter somewhere.
As it turned out, however, the boy had apparently been outside the entire time. Despite this, the police told news agency TT on Monday that they did not think the boy had died from hypothermia.
According to the police, they will spend Monday morning going from door to door in the neighbourhood and continuing the forensic investigation of the area where the boy was found.
“We’d appreciate any information the general public may be able to provide,” Loeffel told TT.
On Monday morning the little boy’s body was taken to the forensic department in Lund where the autopsy will be performed.
The Scanpix photographer on the scene reported that the mood in the area was subdued on Monday morning. Hardly any locals were seen on the streets in Ljungby.
“People are terrified here and many are afraid to let their children go to school,” Mikael Fritzon told TT.
The authorities have informed all local school principals of the situation.
“They will be following the crisis procedures, meaning staff will be answering questions and handling concerns in order to speak to the students about what’s happened,” said Carina Karlund, head of information at Ljungby municipality, to TT.