Police searching for a Washington toddler said Monday they have received 900 tips about the missing boy, but have no "high priority actionable items."
Bellevue Police Maj. Mike Johnson said 300 law enforcement people are working on the disappearance of 2-year-old Sky Metalwala, who has been missing for nine days
Over the weekend they expanded the search around his mother's apartment and the section of road where she said her son disappeared after she left him alone in an unlocked car to go for gas.
Investigators still want Julia Biryukova to answer more questions, but Johnson wouldn't call her uncooperative.
Johnson said investigators lack evidence to move the disappearance from a missing person to a criminal case.
He said during a news conference Monday that "All theories are still viable and we have not ruled anything out."
Biryukova told police that she was driving her sick son to a hospital when she ran out of gas. She claimed she left the boy buckled into his car seat, sleeping, while she and her 4-year-old daughter walked to a Chevron gas station, about a mile away. When the two returned to the unlocked car, the child was gone, according to Biryukova.
But investigators said Biryukova's story "doesn't add up," and is very similar to an episode of "Law & Order: SVU," which aired a day before the child disappeared.
They also said Biryukova's car had "a sufficient amount of gas" when it was examined by authorities.
Biryukova and the child's father, Solomon Metalwala, are in the midst of a bitter divorce battle.
Metalwala told ABC News on Monday that he believes his son's disappearance is related to a court decision granting him visitation rights.
In divorce court documents, Metalwala said his wife suffers from mental illness and had dreams about killing the couple's children, according to Fox affiliate KCPQ.
Biryukova has accused Metalwala of domestic violence, claiming that he assaulted her in front of the children in December 2009.
Police have said they suspect foul play in the disappearance of Sky, who is of Indian and Caucasian descent with brown eyes and dark hair. He was last seen wearing a dark green hooded sweatshirt and blue and gray-striped pants, according to his mother.
Biryukova had previously been cited for leaving a child unattended in a vehicle. In 2009, Redmond police cited Biryukova and Metalwala for leaving a child unattended in a vehicle. The case was dismissed after they agreed to probation, community service and a 10-week parenting class.
The Associated Press contributed to this report.