He was last seen by two neighbours walking alone on a street of Haut-Vernet.
Dozens of French police and soldiers backed by helicopter searched the terrain around a tiny hamlet in the French Alps on Tuesday, saying they still hoped to find a toddler who has been missing for three days.
Emile, who is two and a half, was staying with his grandparents when he went missing on Saturday. He was last seen by two neighbours walking alone on a street of Haut-Vernet, a tiny village of 25 inhabitants at an altitude of around 1,200 metres (4,000 feet).
"We're not stopping the search, we are not losing hope," the local prefect, Marc Chappuis, told reporters late Monday.
But after 48 hours of combing through the area without success, the search was now becoming "more targeted" and "more selective", he said.
Authorities said that large-scale searches involving volunteers which took place on Monday had been discontinued.
Instead 80 military police officers were deployed for a targeted search on Tuesday, backed up by a dozen soldiers specialised in the clearing of terrain, search-and-rescue dogs and a helicopter.
"The work now will be very detail-oriented," local prosecutor Remy Avon said.
This included the analysis of local phone records to determine "what phone calls were made, by whom and to whom", around the time of the disappearance, he said.
Several witnesses had been questioned and houses in the hamlet searched, he said.
Specialist forensic units have also been called in, and more locals are set to be interviewed.
The terrain in the search zone is hilly and craggy with many streams, and the region has been hit by a heat wave, with temperatures forecast to reach 34 Celsius (93 Fahrenheit) on Tuesday.
"All possible explanations are on the table, we're not favouring any, and we're not ruling any out," the prosecutor said.
- 'Looked out for the smallest clue' -
The search has focused on an area of five kilometres (three miles) around the hamlet.
"The child should have been found after 48 hours in that perimeter," said Chappuis.
Police, still hoping for a breakthrough thanks to witness statements, have circulated a picture of the blond and hazel-eyed boy who was wearing a yellow top, white shorts and hiking shoes the day he disappeared.
The site is off-limits to outsiders as of Tuesday, prosecutor Avon said.
Hundreds of volunteers have taken part in efforts to find the boy.
"We took part in a big search this morning with 50 other people," said Roxane, 19, who came with two friends to help on Monday.
"There was a gap of two metres (7 feet) between each of us, we looked in the fields, and in the woods. We looked out for the smallest clue, maybe an item of clothing or a shoe he could have lost," she said.
Prosecutors have given no information about the number of adults present in the grandparents' house when Emile disappeared.
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