The cause of death for both Samantha Ross, 7, and Paul Ross, 11 months, was asphyxia by airway obstruction and the manner of death was homicide, Somerset County Prosecutor Michael H. Robertson said.
The Skillman siblings were found bound and restrained in the back of their mom Yuhwei Chou's car early Tuesday morning, the prosecutor said.
Chou was charged with two counts of first-degree murder.
The Ross siblings were mourned by their babysitters as curious, bright and happy children.
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