Updated

The stepmother of a 5-year-old Kansas boy who has been missing for four days was arrested Wednesday on two counts of endangering a child, Wichita police said.

Emily Glass, 26, was booked into the Sedgwick County jail in connection with Saturday's disappearance of Lucas Hernandez. She has not been formally charged.

"This is now a criminal investigation," Sedgwick County Deputy Chief Gavin Seiler said.

Authorities have said Hernandez reported Lucas missing on Saturday and told police she last saw the boy at their home before she took a shower and fell asleep.

Despite extensive searches by more than 100 local, state and FBI officials, the boy has not been found.

The two counts of child endangerment relate to Lucas and a 1-year-old child, Seiler said, but he would not elaborate. He also would not say what led to Glass' arrest. Relatives have said Glass has a young daughter.

When asked if authorities believe the investigation is a homicide, Seiler said, "We hope we are able to find Lucas and that he is alive and well."

More charges are possible in the case, Seiler added.

Police did not issue an Amber Alert when Lucas disappeared, saying they have found no evidence that he was abducted.

The boy's 33-year-old father has custody of him and frequently works out of town, relatives told The Wichita Eagle. Police won't say where the father was when his son disappeared.

Lucas has brown hair and brown eyes, weighs 60 pounds and is four feet tall. He was last seen wearing black sweats, white socks and a gray shirt with a bear on it.

It was not immediately clear if Glass had retained an attorney.