LA VISTA, Neb. (AP) — The search for a missing autistic 11-year-old boy in eastern Nebraska entered its third day Wednesday, and police leading the effort said the child had searched online for “how to hide from police” before his disappearance.

Ryan Larsen walked out of his elementary school Monday morning and hasn’t been seen since, police said. The child has a history of hiding from his family and has a habit of hiding in small spaces, police said. But officials said he’s never been missing for days at a time.

Investigators said the family’s computer showed Ryan had conducted online searches using the phrases “hiding from the police,” “hiding underground,” and “how to avoid being spotted.”

Police have already checked manholes and a nearby pond, but turned up nothing. At least one La Vista business captured video of Ryan in the area between noon to 2 p.m. on Monday, police said.

About 100 volunteers turned out in recent days to search for the boy, joining police in the effort, but police are now considering other options after autism experts warned that the heavy show of police and volunteers could be pushing the child further into hiding.