A suspect, a 24-year-old man working in the huge industrial zone of the port city, appeared before a prosecutor on Monday, along with three flatmates charged with not having informed the police.
Capital punishment is still in force in the kingdom but has not been applied since 1993.
A “justice for Adnan” campaign calling the killer to be executed has picked up steam since the boy’s body was found on Friday night buried under a tree near his home.
His family contacted police when the boy went missing four days earlier and his picture was widely circulated on social media.
Internet users unearthed low-definition footage appearing to show Adnan with a stranger.
The suspect was identified and arrested for “intentional homicide of a minor and indecent assault”, Moroccan police said.
According to an initial investigation, he took the boy to his rented apartment, then “sexually assaulted him and committed intentional homicide”, before burying him.
Moroccan media said that he later sent a ransom demand to the parents by text from his own phone, making them believe he was still alive.
King Mohammed VI late Monday sent a letter of condolence to the boy’s family, condemning the “odious criminal act”, the royal palace said.
AFP