The mother of three-year-old Mikaeel Kular is the person who has been detained in police custody in connection with the discovery of a body that police "strongly believe" to be Mikaeel, ITV News understands.
Rosdeep Kular, 33, reported the toddler as missing on Wednesday night.
A body was discovered shortly before midnight on Friday in Fife.
A timeline of events surrounding the disappearance of three-year-old Mikaeel Kular.
What tools and techniques will police be deploying in their effort to reunite Edinburgh toddler Mikaeel Kular with his family?
Hundreds of people have gathered to join the search for a missing three-year-old boy who was last seen on Wednesday night.