Police say Michael Deangelo, 32, was speeding at 120 miles per hour last Sunday when he rear-ended a family going to get ice cream.
The crash killed a father and his two kids, and now his six-year-old granddaughter has also died.
Tests indicate Deangelo had cocaine and fentanyl in his system.
He now faces several charges including vehicular manslaughter.
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A GoFundMe page has been set up to pay for funerals and ongoing medical expenses of the victims.
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