MADISON, Wis. –

A shooting at Abundant Life Christian School in Madison, Wisconsin, has sparked an extensive investigation focused on digital evidence and a document called Natalie Rupnow’s Manifesto.

Police Chief Shon Barnes announced in a press conference that authorities are working to authenticate the document shared on social media, stressing that its authenticity has not been confirmed.

“We are working to authenticate the documents that you see online that some call a manifesto, and as soon as we do that we will let you know,” Barnes said. “The process for this is to review original documents that may have been taken from the suspect’s home and review information that may be on laptops or computers to determine if that document came from our suspect.”

Investigators are currently working to determine the origin of the document and who shared it online.

“We ask that you do not share the document or spread any information that may be false. Our department will update this document as soon as we can. There are always signs of a school shooting before it happens,” Barnes said, adding that officials are investigating her social media accounts and online footprint.

ABC News reports that online accounts linked to Rupnow are being investigated by police and contain multiple mentions of shooters and violence.

Investigators conducted a thorough search of the house in Rupnow to determine the motive for the incident. Chief Barnes indicated that the motive appeared to be a “combination of factors,” but specific details cannot be released due to the ongoing investigation.

Police are also investigating whether bullying played a role in the incident and have spoken to students to find out if bullying was a contributing factor.

According to officials, the suspect’s family is cooperating with law enforcement. Family friends replaced a door to Rupnow’s home after it was broken into during a police investigation on Monday.

The FBI has joined local authorities in the investigation, particularly in reviewing the digital evidence.

Police previously said Rupnow used a handgun in the shooting. 12 News Investigates has learned that the Bureau of Alcohol, Tobacco and Firearms has sent an expedited trace of this firearm to Madison police, which will show investigators who bought it, where and when. ATF told 12 News it could not legally share the information. Madison police, who can share this information, did not respond to a question about expedited tracing.

Police are asking anyone with information about the suspects’ online activity or insight into their emotions leading up to the incident to contact Madison Area Crime Stoppers at 608-266-6014 or P3 Tips.

WATCH the Madison Police Department’s update on the alleged Manifest investigation.