Schoolgirl April Jones remained missing on Thursday despite a third night of extensive police searches and a desperate plea from the five-year-old's distraught mother.
Detectives are continuing to question abduction suspect Mark Bridger about the youngster's disappearance after they were granted a 12-hour custody extension on Wednesday night.
The former soldier, 46, was arrested by officers on Tuesday after cerebral palsy-sufferer April vanished near her home in the mid-Wales town of Machynlleth the night before.
Rescue team search for missing girl April Jones near Machynlleth
Bridger has been interviewed on at least two occasions and police will have to decide whether to apply to a court for a warrant of further detention when his custody time limit expires later this morning.
He was picked up by officers while on foot - with police later confirming he was wearing camouflage-style clothing and that his blue L Reg Land Rover had been retrieved from a repair garage in Machynlleth.
More than 220 police officers and mountain rescue personnel have joined the operation to find April, who is reportedly supposed to take daily medication for her health problems.
Search teams have been combing Powys's rugged terrain since she was seen being lured into a vehicle on Monday evening and officers have vowed to leave no stone unturned as they scour the area around the market town.
Bridger was walking in the direction of Machynlleth when he was detained by police
Superintendent Ian John, of Dyfed Powys Police, said the scale of the investigation was "unprecedented".
"The search operation is continuing to grow and grow at quite a pace," he added.
"We've got over 100 mountain rescue experts, 100 police-trained search officers, 20 dog-handlers, two vessels to search the river, a team of kayakers, as well as the Dyfed Powys Police marine unit."
Three UK experts have also been drafted in to help with the hunt.
John continued: "There are a large number of sites we are looking at.
"They are very varied in nature and the terrain that we are working in and the geography that we are working in is very challenging. It's been described to me as a hostile environment.
"By that, I mean the ground is quite treacherous and we have had a lot of rain."
April Jones has been missing since Monday
Police said they had received more than 1,600 messages from the public in relation to the case and are actively working through all the information to prioritise inquiries.
Detectives are also focusing specific search activity at more than 20 scenes which are continuing.
One of the areas is a farmhouse where Bridger is believed to have lived recently and specialist teams have also been combing the area along the Dyfi river.
Bridger has young daughters who are known to have played with April in the area where she was snatched, near her home on the Bryn-y-Gog estate where she lives with her mother Coral, 40.
The two girls, believed to be aged seven and 10, live less than 200 yards from April's home.
Both girls have a step-sister who is the same age as April and who also regularly played with her.
April's mother yesterday begged for help in finding her daughter as she made an emotional public appeal.
Ms Jones sobbed as she said: "There must be someone out there who knows where she is and can help the police find her. We are desperate for any news.
"April is only five years old. Please, please, help find her."
Police have also took the unusual step of confirming Bridger's identity as they issued photographs of him and his blue Land Rover Discovery, registration number L503 MEP.
Coral Jones made a heartfelt plea for information for her daughter
They appealed for information about his movements and the whereabouts of the four-wheel-drive between Monday evening and Tuesday afternoon when he was arrested.
April has been missing since around 7pm on 1 October when she vanished while playing with friends in the Bryn-y-Gog estate.
She was seen to get into a car, believed to be a left-hand drive Land Rover Discovery, apparently of her own free will.
Since then, hundreds of people from the local area and further afield have helped search for the little girl, but police have now urged them to allow specialist teams to take over.