FBI: Missing children from Washington may be in Phoenix area

The Federal Bureau of Investigation is asking Arizona residents to be on the lookout for two children who were reported missing out of Washington.

The agency believes Sage and Isaac Cook may in the company of their mother, Faye Ku, and their toddler half-brother, Zephyr Ku. Officials say Ku does not have custody of her sons.

Investigators say Ku, 41, attempted to take the children out of the country in 2013. They were detained before boarding a flight to Taiwan. Ku was arrested and charged with custodial interference.

The boys are 9 and 15-years-old. They were last seen on August 28, 2015 at Los Angeles International Airport.

FBI investigators say Ku has contacts in the Phoenix area.

"Sage and Isaac spend most of the year in Bellevue, Washington, where they live with their father, who has primary custody. Investigators believe Ku may have forged a 'supervised visit' court order, leading the children's father to send them to California for a brief visit," stated Ayn Dietrich-Williams of the FBI's Seattle Division.

Dietrich-Williams continued, "There is a Washington state felony warrant for custodial interference issued for Faye. The victim's father has had full custody of the children since 2014, and--before that--shared custody since his divorce with Ku in 2009. Investigators found that Ku left behind personal belongings at her California residence that would have helped law enforcement track her whereabouts. In a letter left at the residence, Ku blamed the children's father of trying to control them and asked them to leave the children alone."

Sage is described as a bi-racial, 5' 6" tall, 109 pounds with brown hair and brown eyes. Isaac is also bi-racial, 4' 6" tall, 64 pounds with brown hair and brown eyes.

If you have any information about this case, call the FBI at (623) 466-1999.