For parents waiting for news of their missing children, some of whom disappeared from their homes and others on walks around their quiet neighborhoods, each day is filled with both hope and heartbreak.
It's an agony that is shared by police departments who are often in a race against time in their desperate search for leads .
ABCNews.com is following five of the most high-profile cases, and here's an update on where the investigations stand. If you have information on any of these cases, call the local police department.
Five-year-old Haleigh Cummings disappeared from her father's Satsuma, Fla., home in February 2009. The last person to see the curly, blond-haired girl was her babysitter, Misty Croslin, who was then just 17-years-old.
This past week, the investigation into her disappearance heated up again as the Putnam County Sheriff's office commissioned as many as 40 divers to search a murky river just five miles from where the girl was last seen. A tip, investigators say, had led them to the river to search for clues in the case.
Late Thursday, Sheriff Jeff Hardy declared that he believed Haleigh was "likely dead" and that investigators would keep working the case until justice was served. Hardy also said that authorities have identified "several" persons of interest in the case for the first time in the 14-month investigation.
Hardy did not release the names of these persons of interests to the public, citing the ongoing investigation.
Haleigh was first reported missing by her father, Ronald Cummings, who made a chilling 911 call, telling a dispatcher, "If I find whoever has my daughter before you all do, I'm killing them. I don't care if I spend the rest of my life in prison."
Croslin and Ronald Cummings, who have married and divorced in the past 14 months, are being held in separate Florida jails on charges of drug trafficking, crimes that are unrelated to Haleigh's disappearance.
Croslin's cousin, 20-year-old Joe Overstreet, was also interviewed by investigators this week in Nashville, Tenn., where he lives. Overstreet had been visiting Haleigh and Croslin when the girl went missing. He has denied any involvement in her disappearance and has never been charged.
The 12-year-old is a sixth grader and was last seen wearing a white-and-pink shirt over a white tank top, blue jeans and white and red shoes. She is described as being 5 feet 1 inch, and approximately 145 pounds with brown eyes and brown hair.
Late Thursday, the FBI doubled the amount of reward money they are now offering from $10,000 to $20,000.
Investigators say they are becoming increasingly convinced that Kayleah was abductedand urged members of the community to be aware of individuals who may behaving strangely, such as someone having trouble sleeping or expressing an unusual interest in the case.
Investigators from the onset have said they have little information as to where the tween may be.
"It's very unusual not to have any indication to point us in a direction one way or another," Greeley Police Chief Jerry Garner said.