(CNN) -- Police arrested a man Friday on suspicion of murder in the case of April Jones, a 5-year-old girl abducted in Wales four days ago.
Suspect Mark Bridger, 46, had previously been arrested on suspicion of her abduction.
Police continue to search for April, who has been missing since Monday evening, when she was snatched from a street near her home in Machynlleth, in a remote corner of mid-Wales.
However, the hunt is now presumed to be for a body rather than in the hope of finding April alive.
The case, which Prime Minister David Cameron described as "every parent's nightmare," has gripped the British media.
Bridger remains in custody and continues to be questioned, said Detective Superintendent Reg Bevan, of Dyfed-Powys Police.
Bevan appealed again for the public to come forward with any information on the movements of Bridger or his vehicle between Monday evening and Tuesday afternoon, when he was first arrested on suspicion of abduction.
April's family has been told about Bridger's arrest on suspicion of murder, he said.
Superintendent Ian John told reporters that the "dynamics of the search have changed" and that only specialist teams would now be involved.
Scores of local volunteers from the small, close-knit community had been helping police and mountain rescue teams hunt for the girl in the town and surrounding hilly and wooded countryside.
April's parents spoke Tuesday of how the abduction of "our beautiful little girl April" had "shattered" the family.
Cameron added his voice to the appeals of April's family and police Thursday, when he urged anyone with information that might help find her to come forward.
There has been no trace of the pretty brown-haired child since she was last seen Monday evening, climbing into a vehicle that then drove off. She had been playing on her bicycle with a friend.
CNN's Laura Perez-Maestro contributed to this report.