"We have a single focus and that's to find Robert," Jim Kerns, Boise Police deputy chief said at a press conference Tuesday. "We're concerned for Robert's welfare."
Family members told police that Robert Manwill was last seen walking out of his home Friday evening on Cherry Lane.
Police initially believed the boy may have gone to an unknown friend's house for a party, but that has since been ruled out as a possibility.
He was possibly wearing a brown shirt with writing on the back "Andy don't need no Mic" or a blue shirt with a superman symbol on the front. He had on blue jeans and black shoes.
Manwill is 4'2' and weighs 50 pounds.
"If somebody's seen him, please, please call the police," said Charles Manwill, the boy's father. "All we want is our little boy back."
Manwill is still missing after an extensive area search Saturday and Sunday by Boise Police, Mountain Search and Rescue, and local volunteers.
About 20 FBI agents and dozens of local residents were assisting in the search over the weekend.
According to police, crews drained the pond at the Oak Ridge Apartments to see if the boy's body could be inside.
As of Monday evening Police say they're following nearly 75 leads. Because of the nature of the leads police would not provide any more details. More than 40 officers assisted with house to house searches.
Polly Gorley is one of more than 120 local volunteers joining forces with the Boise Police.
"I'm not familiar with the family, but if it was my family I'd sure want everybody here," Gorley said.
Charles said his son wanted to go to a birthday party, but his mother said no. And that's when the boy went missing.
"This is the most important investigation we've had in a long time," said Michael Masterson, Boise Police chief.
Police have also been and continue to interview registered sex offenders in the area where Robert was last seen.
Police say on Tuesday they will expand their search by another half mile radius.
"Robert is an 8-year-old little guy that needs our help," Kerns said. "We're hopeful we'll find Robert."
Police have set up a special phone line and e-mail address to make it easy for anyone who to contact them with information: (208) 570-6457 - and firstname.lastname@example.org.