Alex and his grandmother, Susan, have been informed.
Since the investigation was launched just over a year ago, detectives in Oldham have explored all possible lines of enquiry.
However, officers have concluded there is insufficient grounds to move forward with any criminal prosecution.
Detective Superintendent Matt Walker, who has led this investigation, said: “Alex and his safety has been at the forefront of our minds and actions since he was found in Toulouse, France in 2023.
“In our commitment to protecting children, we felt it was important that the circumstances of Alex’s disappearance be properly and thoroughly investigated.
"I led a dedicated team to do exactly that when Alex was first found, and this has continued since.
“We have consulted with various partners, such as a complex case CPS lawyer and the National Crime Agency throughout, and concluded there would be no realistic chance of criminal prosecution.
“Given this, the right thing to do is bring closure to this chapter of Alex and his family’s lives, particularly as this is the outcome they wished for.
"Alex is now an adult, safe, and reintegrated with life back in Greater Manchester surrounded by those who love him, which ultimately is the priority.”
