By Dakin Andone, CNN

(CNN) — Police have identified the shooter in Monday’s deadly attack on a Madison, Wisconsin, private Christian school as a 15-year-old female student as they investigate the latest school shooting to devastate an American community.

Natalie Rupnow – who went by Samantha – was found dead when officers responded to Abundant Life Christian School. Evidence suggests she died of a self-inflicted gunshot wound, Madison Police Chief Shon Barnes said at a news conference late Monday.

A staff member and another student were killed in the attack, while six others were injured, police have said, including two students hospitalized in critical condition.

While the victims recover, authorities are examining Rupnow’s background, probing writings allegedly connected to her and tracing the history of the gun she used.

Here’s what we know:

Motive is authorities’ ‘top priority’

Investigators’ “top priority” is determining the shooter’s motive, Barnes said at a news conference Tuesday afternoon.

“But at this time, it appears that the motive was a combination of factors,” he said, though he declined to provide more details.

Police are speaking to students to determine whether bullying was one of the factors, Barnes said.

“Some have asked if people were specifically targeted. Everyone was targeted in this incident, and everyone was put in equal danger,” he added.

Authorities are aware, the chief said, of a “document” that had “been widely shared on social media.”

“At this time we cannot verify its authenticity,” the chief said. “We have detectives working today to determine where this document originated, and who actually shared it online.”

Police said in an update Wednesday that authenticating the document “involves identifying whether the original document exists on the suspect’s personal devices, such as a cell phone or laptop, and appears to have been originally created on a device they own.”

Police are also examining the shooter’s activity online, Barnes told reporters. Officials are not releasing “specifics about these social media accounts,” but he encouraged anyone who knew the shooter or had insight into her feelings prior to the shooting to contact investigators.

Mackynzie Wilson, a sophomore at Abundant Life Christian School whose locker was next to the shooter’s, said she “didn’t expect that from her.”

“She was really quiet. She didn’t really have any friends and she just seemed really lonely,” Wilson said. “It wasn’t like she was trying to fit in. She seemed very content being alone.”

It’s relatively rare for a school shooter to be a female: CNN has documented 83 school shootings in 2024, and of the 59 in which the gender identity of the suspected shooter was available, only two were female. The others involved either lone male suspects or a group of male suspects.

Investigation uncovers alleged communication between shooter and California man

Authorities believe Rupnow communicated with Alexander Paffendorf, a 20-year-old man in Carlsbad, California, who was planning a mass shooting with her, according to San Diego County court documents.

FBI agents stopped and detained Paffendorf on December 17. During an FBI interview, Paffendorf admitted to telling Rupnow “that he would arm himself with explosives and a gun and that he would target a government building.” FBI agents saw these messages, according to the documents.

A California judge issued a restraining order on Tuesday against Paffendorf under the state’s gun red flag law, effective until December 23, with a hearing scheduled for January 3. The order requires him to turn over his guns and ammunition to authorities within 48 hours, unless police ask for them sooner.

It’s not clear whether Paffendorf remains detained. CNN has attempted to reach him for comment.

CNN also has reached out to Carlsbad police and the FBI for more information.

Authorities are uncertain whether the attack was aimed at specific individuals or when it was planned, the police chief told the AP.

“I do not know if she planned it that day or if she planned it a week prior,” Barnes has said of the shooter. “To me, bringing a gun to school to hurt people is planning. And so we don’t know what the premeditation is.”

The gun

Two guns were recovered at the school, but only one was used in the shooting, Madison police said in a Wednesday news release.

The Bureau of Alcohol, Tobacco, Firearms and Explosives completed its data trace and provided it to police, but they are not providing any information on the guns “as it could jeopardize our investigation,” police said in the release.

While it’s not yet clear who owns the gun used or where it originated, Rupnow’s father posted a Facebook photo in August of his daughter at a shooting range.

Jeff Rupnow’s cover photo posted in August shows his daughter shooting skeet.

She can be seen wearing a black shirt with the name of the band KMFDM. The German industrial rock band’s lyrics were cited by the students who carried out the 1999 massacre at Columbine High School in Colorado, where 13 people were killed, CNN has reported.

KMFDM issued a statement at the time condemning the 1999 attack and expressed sympathy for the victims, adding their music was intended to stand against violence, according to Reuters.

In a comment on the photo, Jeff Rupnow replied to someone who asked whether the person in the photo is his child, writing, “sure is!!!! We joined NBSC this spring, and we have been loving … every second of it!”

North Bristol Sportsman’s Club (NBSC) is a shooting range in Dane County. CNN has reached out to the group for comment.

Parents are cooperating with investigators

Rupnow’s family is cooperating with police, Barnes said Monday, acknowledging that a heavy police presence at a home on the north side of Madison was related to the shooting.

Rupnow’s parents have been married to each other and divorced from each other twice, with court orders mandating a complicated schedule requiring the teen to split time between her mother’s and father’s homes, which are 30 to 45 minutes apart, multiple times per week, according to court records obtained by CNN Wednesday. Her parents shared custody, records show, and a mediation agreement from July 2022 notes their daughter was enrolled in therapy and the parents were encouraged to participate. The documents did not detail how long Rupnow was in treatment or the type of therapy.

Rupnow’s parents – Jeff and Mellissa Rupnow – have not responded to CNN’s repeated requests for comment.

It’s unclear whether the shooter’s parents owned or possessed the gun used in the shooting, Barnes told CNN. Police, together with the district attorney’s office, will “want to look at if the parents may have been negligent,” he said.

“But at this time, that does not appear to be the case.”

Both federal and Wisconsin law generally make it illegal for someone younger than 18 to possess a firearm. State law similarly makes it illegal for any person to intentionally sell, loan or give a dangerous weapon to someone younger than 18. However, there are exceptions that allow a minor to possess a firearm for target practice under adult supervision, for use in the armed forces or for hunting.

Wisconsin also has a child access firearm law that makes it illegal to recklessly store a loaded firearm within reach or easy access of a child younger than 14.

Prosecutors in recent years have taken steps to hold accountable parents who provided their children the firearms they would go on to use in school shootings, testing the limits of who could be deemed responsible. Two such cases followed school shootings at an Oxford, Michigan, high school in 2021 and a Winder, Georgia, high school in September.

CNN’s Amanda Musa, Chris Boyette, Michelle Watson, Eric Levenson, Holly Yan, Sarah Dewberry, Jillian Sykes, Caroll Alvarado, Taylor Galgano, Hanna Park and Taylor Romine contributed to this report.

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