A suspect was arrested a few weeks later, and now puzzled neighbors and family members are wondering - why did officers and investigators return to the scene of the shooting on Saturday?
Officials will only say they are looking for evidence related to the deadly shooting. And that's all they will say.
The search is happening on eight acres of private property - in heavy brush partly on a steep hillside in an area that can't be seen from the roadway.
Molly was killed June 1 as she walked down the road with friends.
Nearly four weeks after that, officers arrested Erick N. Walker, 27, of Marysville, based on ballistics evidence, a gun purchase and damage to a car that allegedly links Walker to the crime.
Snohomish County prosecutors say Walker "exhibited extreme indifference to human life" that night when he opened fire on a group of girls, killing Molly as she was celebrating her birthday with friends.
Walker is also accused of firing bullets into four homes in Marysville and Lake Stevens.
Detectives believe he acted alone - that he committed the drive-by shooting after drinking at a pub.
Walker has denied any involvement in the shooting and has pleaded not guilty to charges of first-degree murder and drive-by shooting. He is being held in Snohomish County Jail on $5 million bail.
While locals are grateful police have the man in custody - the renewed search for evidence on Saturday makes some wonder if it's a sign that investigators do not have a strong case.
"I guess that does show they're looking for all the evidence they need to find, but it also makes me a little suspicious that they haven't - why are they stll looking for it if they already found him and he did shoot her," says one neighbor. "I mean, what else are they looking for?"
About 30 volunteer search-and-rescue people assisted a half-dozen officers from the Snohomish County Sheriff's Major Crimes Unit.
They started about 9 a.m. Saturday and expect to spend the rest of the day hunting for whatever they're hunting for.