LAKEWOOD, Wash. -- The FBI has joined the investigation into the death of Adre'anna Jackson, the 10-year-old girl whose remains were found in some bushes in Lakewood on Tuesday, KIRO 7 Eyewitness News reported.

Detectives continued to search the area for more bones and other evidence Wednesday. FBI investigators set up a grid to make sure their evidence recovery team scours every square inch of the footfall field-sized vacant lot where the bones were found, KIRO-TV reported.

Video: Intense Search For Evidence In Adre'anna Jackson Case

"It's going to be a carefully, methodically well-planned, comprehensive grid-by-grid search for all the evidence that might be in that field," said Lakewood Police Chief Larry Saunders.

Investigators were planning to bring in heavy equipment to clear brush Thursday.

As search teams from the Green River Task force helped plot out the search area, friends of Adre'anna put up a memorial nearby.

A fourth-grade friend of Adre'anna left a stuffed animal and a prayer.

"We'd draw together, and play together," she said. "I hope she goes to heaven."

Adre'anna disappeared Dec. 2 after walking to her school, which was closed for the day because of snow.