A 33-year-old woman will appear in a Scottish court after being arrested and charged in connection with the death of three-year-old Mikaeel Kular.
Police did not name the woman, although it has been widely reported that Rosdeep Kular, the mother of the missing Edinburgh boy, was being questioned by officers after a child's body was discovered in Fife, kilometres from his home.
The development was announced late Saturday (GMT) by Police Scotland Assistant Chief Constable Malcolm Graham.
"During the course of today, the investigation into the disappearance of Mikaeel Kular has continued at pace," he said.
"Following formal identification, I can now confirm that a 33-year-old woman has been arrested and charged in connection with Mikaeel's death.
"The woman is expected to appear at Edinburgh Sheriff Court on Monday."
A major police investigation was launched to trace Mikaeel after he was reported missing from his home in Edinburgh's Ferry Gait Crescent on Thursday.
More than 200 members of the public joined police and other agencies in their searches for the youngster in the Drylaw area of the capital on Friday.
Officers searching for the three-year-old found remains - now identified as those of Mikaeel - in Kirkcaldy, Fife, shortly before midnight that day.
Mr Graham expressed his thanks to all those who aided police in recent days.
More than 500 calls were made by the public to a dedicated phone line set up after Mikaeel's disappearance, he revealed.
"I would like to again recognise the overwhelming public assistance that Police Scotland have received during the course of this very complex investigation," he said.
"This includes his family and friends, with whom our thoughts remain."
Mr Graham said he would be unable to answer further questions about the investigation.
Mikaeel's body was removed from a wooded area behind a property in Dunvegan Avenue, Kirkcaldy.
Pandeep Kular, 37, Mikaeel's aunt, sobbed as she told the Sunday People newspaper: "We're devastated. I'm with the kids."
She said she had not spoken with her sister, saying: "I'm not aware of anything. I'm just with my family in the house. That's all I can say. We've just lost him."
Floral tributes, soft toys and candles have been placed at a small park in the Drylaw area, around the corner from the flat where Mikaeel lived on Ferry Gait Crescent.