LEESBURG, Fla. -- Investigators in the case of a missing 2-year-old are trying to verify the whereabouts of the boy's mother after she declined to take a polygraph test in connection with the toddler's disappearance, according to Local 6 News.

The boy's father passed a polygraph test, Local 6 News has learned.

According to authorities, Trenton Duckett was last seen in his room at 7 p.m. Sunday. His mother first noticed he was missing around 9 p.m. Leesburg police said a screen on a window in the boy's room was cut and that he was apparently taken through the opening.

Thursday, authorities said they are following a new course in the investigation.

"Detectives are changing the focus of their investigation," Local 6's Mike Deforest said. "Until now, authorities were looking for witnesses who saw the child's father the weekend of the disappearance."

Joshua Duckett has repeatedly told police that he was at his mother's house and after a lie-detector test, it appears that authorities believe his alibi, Local 6 News reported.

"They are encouraged by the timeline that has been developed so far for his whereabouts and the timeline for Saturday and Sunday," Leesburg police Captain Steve Rockefeller said.

"What remains unverified is the whereabouts of the 2-year-old's mother, Melinda Duckett," DeForest said.

Duckett told Local 6 News that the day before Trenton vanished, she and the child were driving around visiting friends and family.

Detectives are still searching for witnesses who can either back up her account or contradict it.

"Joshua Duckett took a polygraph, and officials were satisfied with his responses," Rockefeller said. "Melinda Duckett has thus far declined to take a polygraph."

Local 6 News learned that police gave a lie-detector test to a friend who was inside Melinda Duckett's home the night she reported her son missing from his bedroom.

"Detectives are satisfied the friend never saw the 2-year-old that night," DeForest said.

Investigators said Duckett's refusal to take a lie detector test does not necessarily mean she is hiding something.

"Just because somebody declines to take a polygraph, that does not indicate anything of that nature," Rockefeller said. "We cannot characterize why somebody would not take one."

Local 6 News was not able to contact Melinda Duckett Thursday night.

Investigators said nobody has been eliminated as a suspect in the case.

Police continued to ask anyone who may have seen Melinda Duckett, Trenton or his father Joshua Duckett on Aug. 26 or 27 to call 800-CALL-FBI.

Watch Local 6 News for more on this story.