"We just want to see what assistance they can provide us. What it will be I don't know," Hewitt said.
The state Department of Justice crime lab has made the processing of evidence in the case its top priority. Meanwhile, the sheriff's office has cancelled all vacations and days off, and investigators are working more than 16-hour days tracking down hundreds of tips that have come into a hotline, Hewitt said.
The attack on Leila, a popular 3rd grader at Jenny Lind Elementary School, apparently was random. The family's home is on a rural street with houses sitting on about an acre apiece.
There were no signs of a burglary or robbery and no indication it was a targeted killing, Hewitt said.
On Tuesday evening, hundreds of people gathered at the school, where Leila's mother, Krystal Walters, tearfully addressed the crowd.
"I just want to thank the entire community and all of our family and friends for all the overwhelming amount of support you've given our family," Walters said. "It will never be forgotten."
AP reporter John Marshall contributed to this from San Francisco.