Officials said she had been removed from the home of her biologial parents and was placed in a foster home.
Prosecutors are considering 13 charges against Mr Treu, including four counts of homicide by intoxicated use of a motor vehicle. Judy Schneider said her 6-year-old grandson doesn't understand that they're gone.
The girls were collecting trash next to a rural highway over the weekend when a pick-up truck hit them.
The traffic crash claimed the lives of Jayna S. Kelley (age 9) of Lake Hallie, Autum A. Helgeson (age 10) of Lake Hallie, Haylee J. Hickle (age 10) and her mother Sara Jo Schneider (age 32) from the Town of Lafayette.
She is being held on a $50,000 cash bond.
Treu said he only took two short "huffs" prior to the crash.More news: China to boost Pakistan defence ties, pats Islamabad on dispute with India
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According to Fox News, Treu's vehicle veered into the ditch where the volunteers were picking up trash, and he drove off after hitting the victims. The passenger, who has not been arrested or charged, told police he grabbed the steering wheel when he saw that Treu "looked out of it" and that the truck was crossing over the road's center line.
Police said that they received a call from a caretaker saying that they had found the boy bleeding from the head and unresponsive.
Police say the troop members were wearing highly visible safety vests.
"We partner with Real Living, so any student in our district, no matter what the circumstance gets 4 free counseling sessions for themselves, as well as every single member of their family", said Eliopoulos.
Haylee also enjoyed painting and working on clay pottery with her mother.
The suspected driver, 21-year-old Colten Treu of Chippewa Falls, fled but later turned himself in several hours later, police said. Temporary representation was with him for his court appearance again Tuesday, and CNN has reached out to the attorney for comment.
As a western Wisconsin community grieves the deaths of three Girl Scouts and a parent who were struck by a pickup truck, authorities still haven't released the names of the victims or a fourth girl who survived. Sokup says he will be charged with four homicide counts.