The father involved in an AMBER Alert out of Seattle on Tuesday night has been charged on an unrelated offense, according to the King County Prosecuting Attorney’s Office.

Nicholas Anthony Antonie, 42, was booked in the King County Correctional Facility on Wednesday and was charged Friday with two counts of felony domestic violence harassment and one count of felony harassment.

Bond was set at $250,000.

Antonie is accused of threatening to kill his mother, sister, and girlfriend's sister, because he blamed them for Child Protective Services seizing his children following Tuesday's AMBER Alert, according to charging documents.

The AMBER Alert was issued for four children after their father and mother took off with them. The family was located in their RV in Spokane County. Police questioned both parents and released them Tuesday night. 

But Seattle police say they continued their investigation and issued a probable cause warrant around 4:30 a.m. Wednesday for the father's arrest for violating a protection order and making threats. 

The Washington State Patrol located the father in his motorhome Wednesday morning and took the man into custody. 

He was transported to the King County Jail to meet Seattle police. 

RELATED: 4 kids in Seattle AMBER Alert found safe, suspects released

Authorities say the children in the AMBER Alert were supposed to be turned over to Child Protective Services on Tuesday. 

Police were concerned that the father was actively fleeing the state after withholding needed medication from his children. Caseworkers say the father threatened to physically harm the kids. 

However, when speaking to reporters after his arrest Tuesday, the father claimed he called 911 himself when he saw the AMBER Alert. 

After the parents were questioned and released, the children were turned over to the Washington State Department of Children, Youth & Families.

Washington State Patrol says this is the fifth AMBER Alert this year.

The U.S. Department of Justice has guidelines to when an AMBER Alert should be issued: First, law enforcement must have a reasonable belief an abduction has occurred. The child involved must be 17 years old or younger. The law enforcement agency must also believe the child is in imminent danger of serious bodily injury. Finally, there must be enough descriptive information about the victim and abduction.

Since the AMBER Alert system began in 2002, close to 1,000 children have been found.