Exclusive: Mother's Desperate Search for Somer's Killer

ORANGE PARK, Fla., Nov. 9, 2009 — -- The nights are the worst. Diena Thompson's mind races. She struggles to fall asleep and wakes up confused. It takes a moment for reality to hit again.

"I keep thinking that she's going to come in and this is just a nightmare and I'm going to wake up," Thompson said in an interview with "Good Morning America" in the living room of her home Friday. "And she's just been at somebody's house spending the night."

But her daughter Somer is not coming home.

Three weeks ago Monday the 7-year-old was walking home from school with her older sister Abby and twin brother Samuel. Her mother was at work. And as usual, the children were to walk home together. Friends' parents would keep an eye on them.

"I know that Samuel had lagged behind talking to a friend," Diena Thompson told "GMA." "And Abby and Somer were together and that -- I'm not sure what happened. Somer got teased a lot. ... She ran ahead, and Abby just figured she'd catch up with her. And when she got to the second crossing guard Somer wasn't there."

Somer was last seen in front of a vacant house on a block she walked every day. Investigators found her body in a Georgia landfill two days later. Thompson does not know exactly how her daughter died. It was recommended that she not view the body.

Her grief is immeasurable. She is anxious and guilt-ridden. But she is speaking out now, at the three-week mark, because she wants the killer put on notice that they are still hunting, and she wants other parents to hear her words.

To date, investigators at the Clay County Sheriffs department in Jacksonville say they have pursued more than 3,000 leads. But still no arrests.

Over the weekend, authorities released sketches of two items that Somer had with her on the day she disappeared, which have never been recovered.

Police ask anyone who has seen the tote bag or zippered round lunch pail to call their tip line at (877) 227-6911.