MIAMI (AP) — The mother of a missing toddler did not respond by Tuesday to an offer that would have given her some protection from prosecution if she told investigators what she knows about her daughter's disappearance.

Officials say 3-year-old Caylee Anthony is probably dead. Her mother, Casey Anthony, missed a 9 a.m. deadline to respond to an offer of limited immunity, a spokeswoman for the state's attorney's office said.

Under the offer, prosecutors could not have used Anthony's statements against her, but they could have used any evidence found as a result.

The decision capped a weekend of twists in the search for Caylee, who hasn't been seen since June. Her mother did not report her missing until July.

A spokeswoman for Anthony's attorney, Jose Baez, declined comment.

Authorities said Monday there was a decomposing body in the trunk of Casey Anthony's car and investigators believe there is a "strong probability" that Caylee is dead.

Anthony, 22, faces charges of child neglect, making false statements and obstructing the investigation into her daughter's disappearance.