The man was shot multiple times in the head and back and received life-threatening injuries while spreading salt on ice and snow-covered paths on Roskildegatan north of Pildammsparken during the early hours of a February morning.
The boy was arrested later that day on suspicion of attempted murder, and has now been charged by Malmö District Court. He has consistently denied the crime.
"I will restrict myself to saying that he denies the crime and involvement in this alleged act," his lawyer Sanna Herlin told news agency TT.
READ ALSO: Teen, 15, held after janitor shot in Malmö
DNA evidence found on the 15-year-old's hands and clothing were used in the investigation, which his lawyer declined to comment on. The prosecutor believes it is possible to demonstrate that the boy had a habit of being present in environments where weapons were present.
He was likely suffering from a mental disorder during the time of the incident, according to doctors who assessed him, and was also likely suffering from one during the investigation.
The weapon used in the shooting has not been found by police, despite their efforts in searching the area including a nearby pond. Several witnesses saw the incident from their homes and the boy is said to have been alone when the shooting took place. The prosecutor said there is no hypothesis over a clear motive.
His lawyer thinks it is striking that he has been detained since being remanded in custody in February:
"A while ago it would have been unthinkable. It shouldn't be like that in Sweden, there should be other solutions".
The janitor's condition became stable at the end of February, though he still has difficulty moving with ease according to newspaper Sydsvenskan.
The trial will start on May 29th and is expected to last between three and four days. In Sweden 15 is the age of criminal responsibility.
Malmö was rocked by a number of shootings in the early months of 2017, including the tragic killing of a 16-year-old in Rosengård in January.
READ ALSO: Minister visits Malmö as shootings continue