Lindsey disappeared while walking home from a friend's house last June.
Investigators from multiple agencies have spent months searching for the girl, and the FBI recently moved in a high-tech command center to coordinate efforts.
Agents with the CARD team have been checking hours of ATM security camera video taken from cash machines throughout McCleary and the surrounding area, looking for anything that seems out of place.
They have also been checking cell phone records to see who was in the area when Lindsey vanished.
"We can start putting a timeline together," FBI Assistant Director Kevin Perkins told Nightline. "And we may see that call and a certain cell phone and, perhaps, our missing individual coming together at a certain place at a certain time."
The agency also has profilers and psychologists analyzing evidence.
Detectives from the sheriff's department are working with the FBI to check new sites that might be connected to the case, and they're also re-searching sites checked previously.
The investigators are also interviewing most of the people in the town, hoping for new leads and watching for unease.
"We're looking for the whole picture, but there are sometimes when you get a gut reaction or gut feeling about a certain individual or their reaction to your questioning," sheriff's Det. Keith Peterson said.
Investigators have talked with more than two-thirds of the town's population.
Drawing on the interviews, searches, security camera video and cell phone data, the FBI has built a model and timeline of the day Lindsey was last seen.
Lindsey's mother, Melissa Baum, thinks someone is holding out.
"I guess what gets me is I know aliens didn't just beam her up and take her away," she said. "Somebody knows something."
Sources tell ABC news that 12 people identified as persons of interest in the case live inside and outside of McCleary, and at least two of those people are considered "high interest" by investigators.
While an arrest may not be imminent, police say the case is active and they are hopeful.
And Lindsey's mom is still spending every day working to find her daughter.
"I don't care who you are," she said. "I just want my Lindsey back safely."