Where is Lindsey Baum? Police, FBI Search for 10-Year-Old

June 30, 2009— -- It was a route Lindsey Baum had taken many times -- a 10-minute walk down a densely populated suburban street between her house and a friend's.

But on Friday evening, the McCleary, Wash., 10-year-old left her friend's house for home and disappeared somewhere along the way.

"I think somebody took her," Melissa Baum said of her daughter, who was ready to enter the sixth grade in the fall. "I'm trying to constantly push away the bad thoughts."

Grays Harbor County Undersheriff Rick Scott said search efforts have escalated in the days since Lindsey's been missing from volunteers on foot -- still the most common tactic used -- to scent dogs, horses, all-terrain vehicles and helicopters.

"We're not ready to give up hope," Scott told ABCNews.com.

Baum said she last saw her daughter when Lindsey, along with her 12-year-old brother, Josh, headed out to Lindsey's friend's house in hopes she could get permission to spend the night at the Baum's house.

Baum said her children began squabbling over the use of Josh's bike on the way there and were stopped by a family friend who sent Josh home to end the argument. Lindsey continued on to her friend's house. When Lindsey's friend found out she couldn't stay the night, Lindsey headed for home around 9:30 p.m.

"When she wasn't home by 10, I started to get nervous," Baum said, adding that 10 p.m. is the curfew for her children.

She began calling Lindsey's cell phone, only to find that her daughter had left it plugged into the charger. Initially thinking that her daughter must have met up with friends in the neighborhood, Baum set out on foot to find her daughter.

But there was no sign of her. Eventually, her friend's parents joined the search by car. Baum even let her daughter's beloved German shepherd Kadence off its leash in hopes the dog would help find her. Finally, around 10:45 p.m., Baum said she called the police.

Baum described her daughter as outgoing, talkative and mature for her age. She loved to read and write and had big plans for her future.

"She insisted when she grows up she's going to be an author and an illustrator and a veterinarian," Baum said.