The man with Shasta, Joseph Edward Duncan III, was arrested and charged with kidnapping, but he has requested a lawyer and is refusing to talk to authorities, Kootenai County Sheriff's Capt. Ben Wolfinger said Sunday.
Duncan won't be appointed a public defender until a court hearing Tuesday, Wolfinger said.
In the meantime, the search for Dylan continues, though investigators say the information they have points to the boy being dead.
"Our goal is to find Dylan one way or another," Wolfinger said.
Investigators haven't revealed what they believe happened to Dylan or how long they believe the boy was alive after the children's mother, 13-year-old brother and their mother's boyfriend were bludgeoned to death in their home on May 16.
Some authorities are convinced that Dylan is dead, CBS News Correspondent Cynthia Bowers reports.
There was no sign of the boy when Shasta was found around 2 a.m. Saturday in the restaurant with Duncan.
Shasta was recognized by a waitress at the restaurant, who called police, and the little girl was reunited that afternoon with her father, Steve Groene. She was reported in good condition at the hospital Sunday, Wolfinger said. The girl's father has declined requests for interviews.
The arrest of Duncan, a 42-year-old from Fargo, N.D., who had spent more a decade in prison for raping a boy at gunpoint when Duncan, has raised many questions and provided few answers.
"Where have Duncan and Shasta and Dylan been the last six weeks? Was Duncan involved in the triple homicide? Were other people involved? Is so, who and where are they?" Wolfinger said.
"I think why is probably the biggest question we have," he said.