Wisconsin school shooter Natalie Samantha Rupnow is pictured

The baby-faced killer who gunned down a fellow student and a teacher at her Wisconsin high school has been pictured. 

Natalie Samantha Rupnow, 15, killed herself after unleashing the massacre at a study hall at Abundant Life Christian School. She also injured six others including two students who were in critical condition.

A substitute teacher and three students had been taken to a hospital with less serious injuries, and two of them had been released by Monday evening.

Rupnow's father Jeff Rupnow shared several images of his daughter throughout the years - all the way back to her birth in 2009. 

The father is cooperating with police as they try to find a motive for the tragedy as well as how the teen accessed the weapon she used, believed to be a 9mm handgun.

The shooter’s parents, who are divorced, jointly shared custody of their child, but the shooter primarily lived with her 42-year-old father, according to court documents. 

Investigators on Tuesday are focused on trying to determine a motive in for the school shooting that left a teacher and a student dead and two other children in critical condition.

Shon Barnes, the police chief in Madison said investigators were aware of a 'manifesto, if you want to call it that, or some type of letter' posted by someone who might have known the shooter, 15-year-old student Natalie Rupnow.

'We haven’t been able to locate that person yet, but that’s something we’re going to work on today,' Barnes told CNN.

'We’ll also be looking through (Rupnow’s) effects, if she had a computer or cell phone, to see if there are any transmissions between her and someone else, and that will give us an idea of what type planning.'

Chief Barnes said they’re trying to put together a timeline of the shooter’s last hours before she went to the school.

Barnes said they’ve asked the ATF to expedite determining the origin of the gun used in the shooting and how the 15-year-old got her hands on it. He said he’s not certain if the weapon was owned or possessed by her parents.

Asked if her parents could be charged with a crime, Barnes said they were voluntarily giving information, but he also wanted to look at whether the parents were negligent. But at this time, he said that doesn’t appear to be the case.

Two prominent cases of parents facing criminal charges after their children are accused in school shootings have come in Michigan and Georgia in recent years.

Jeff Rupnow's posted a picture on Facebook showing his daughter at a shooting range. He was asked by a friend if it was his daughter in the image. He replied: 'Joined NBSC (North Bristol Shooting Club) this spring and we have been loving every second of it. 

The NBSC - or North Bristol Sportsman's Club - is a gun club in Sun Prairie, a suburb of Madison, offering annual family memberships for just $90, according to its website.

The club was founded in 1970 and has more than 600 members. The Rupnows' alleged membership has not yet been confirmed by the club. DailyMail.com has approached the NBSC for comment.

Abundant Life is a nondenominational Christian school — prekindergarten through high school — with approximately 420 students in Madison, the state capital.

The school does not have metal detectors but uses other security measures including cameras.

Children and families were reunited at a health clinic about a mile away. Parents pressed children against their chests while others squeezed hands and shoulders as they walked side by side. One girl was comforted with an adult-size coat around her shoulders as she moved to a parking lot teeming with police vehicles.

The school shooting was the latest among dozens across the U.S. in recent years, including especially deadly ones in Newtown, Connecticut; Parkland, Florida; and Uvalde, Texas.

Firearms were the leading cause of death among children in 2020 and 2021, according to KFF, a nonprofit that researches health care issues.