A 36-year-old Somerset County mother found with the lifeless bodies of her two young children told police she had planned their murders for a week, according to an affidavit of probable cause.

Yuhwei Chou, of the Skillman section of Montgomery, is charged with the murders of her 7-year-old daughter and 10-month old son, Samatha Ross and Paul Ross.

The older child had her wrists zip-tied together and both had duct tape over their mouths when found on Tuesday morning in their booster and car seats, according to the affidavit as first reported by MyCentralJersey.com.

They were pronounced dead at the scene in a car off a road in Hillsborough.

Chou’s hands also were zip-tied to the steering wheel when a bystander found the disabled Toyota Carolla, the affidavit said, alongside Mountain View Road, between E. Mountain Road and Pleasant View Road.

She told police she had suffocated her children on Monday afternoon, going into chilling detail about the day’s events — from a stop for lunch at Wawa before buying duct tape and zip ties at a hardware store, according to the affidavit.

Chou said she had begun to tape her 7-year-old’s face while outside a sports complex in Hillsborough, but changed her mind after seeing a bystander nearby.

She then parked in a “hunting area” along Mountainview Road, where she climbed into the backseat and said she carried out her deadly plan, suffocating her daughter and son.

Autopsy results were pending on the Ross children Thursday, as was a detention hearing for Chou, who remained in police custody.

Property records show a four-bedroom house on Pine Brae Drive in Skillman as belonging to Chou and James Ross.

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