A reward was increased to $4,000 Friday for information on the whereabouts of a 5-year-old Jacksonville, Florida, girl missing since Wednesday.

Jacksonville Crimestoppers increased the reward three days after the child's mother said Taylor Rose Williams was missing from her bed at 7 a.m. Wednesday and the family home's back door was open.

An Amber Alert has been issued.

Sheriff Mike Williams told reporters the girl had not been seen for several weeks and mother Brianna Williams, 27, was the last person to see her but she had stopped cooperating with investigators.

“Yesterday we were talking to her about some inconsistencies in her statement and that’s when she chose to stop cooperating with us,” Williams told reporters. “We need her to cooperate with his investigation to help us find her daughter.”

Sheriff Williams said the mother was not under arrest.

“We won’t take the steps to say she is a suspect, but we do know that her daughter is missing and she was the last person to see her,” Williams told a Thursday news briefing. “We do not believe the daughter walked away.”

Investigators expressed concerns about Taylor’s well-being, given her age and the urgency needed to safely find her and traveled to Alabama to speak with Taylor’s biological father, Maurice Tate.

“It's very urgent that we find her as quickly as possible,” Jacksonville Sheriff's Office Chief of Investigations T.K. Waters said during a Wednesday media briefing. “We'll work until we can't work anymore.”

Jacksonville CNN-affiliate, WJXT, reported Brianna Williams is a Navy petty officer at the Tactical Operations Center at Naval Air Station Jacksonville.

“We remain hopeful that we’ll find Taylor,” Sheriff Williams said. “We’re not going to stop in our efforts to locate her, and there’s not one scenario or theory that we’re not exploring.”

Taylor is described as standing 3-feet tall, weighing 50 pounds with brown eyes and black hair.

This image shows police officers after a shooting at Seattle Pacific University in Seattle on June 5, 2014. Mat Hayward/Getty Images