Natalie Rupnow's accomplice Alexander Paffendorf, 20, unmasked... as police reveal how he 'helped her plot Wisconsin shooting'

The California man accused of plotting a coordinated attack with Wisconsin school shooter Natalie Rupnow has been pictured for the first time.

Alexander Paffendorf, 20, of Carlsbad, was detained by FBI agents on suspicion of 'plotting' to coordinate a mass shooting at an undisclosed government building.

Paffendorf admitted to agents that he had been messaging 15-year-old Rupnow about attacking a government building with a gun and explosives, according to court documents made public Wednesday.

A San Diego judge judge issued a restraining order Tuesday under California's gun red flag law against Paffendorf, requiring him to surrender any firearms and ammunition to police within 48 hours, and prohibited him from acquiring any more. 

Shortly afterwards, neighbors told CBS 8 they saw more than a dozen police cars enter the apartment complex where Paffendorf lives on Tuesday night and saw officers coming out of the building carrying what was described as a 'black gun box.'

The order doesn't say what building he had targeted or when he planned to launch his attack. It also doesn't detail his interactions with Rupnow except to state that the man was plotting a mass shooting with her. 

Paffendorf appears to live at the property raided by police with his father, address records revealed. A court hearing for Paffendorf is scheduled for January 3.

The 20-year-old seemingly has maintained a low-profile online, with DailyMail.com finding no social media accounts associated with his name. He is also 'touchy about getting his photo taken', according to a Facebook post from an account apparently linked to his father.

It was not immediately clear how Paffendorf knew Rupnow, and Madison Police Chief Shon Barnes told the Journal Sentinel he did not have any information about the arrest in California, and referred questions to the FBI. 

DailyMail.com has approached the FBI, San Diego Police and San Diego Superior Court for comment.

Police are still investigating why the 15-year-old student at Abundant Life Christian School in Madison shot and killed a fellow student and teacher on Monday before shooting herself, Barnes said. 

Two other students who were shot remained in critical condition on Wednesday. 

The student who was killed in Monday's school shooting was identified in an obituary released Wednesday as Rubi Patricia Vergara, 14, of Madison. 

She was a freshman at the school and 'an avid reader, loved art, singing and playing keyboard in the family worship band,' according to the obituary.

The Dane County medical examiner Wednesday evening identified the teacher who was killed as 42-year-old Erin Michelle West.

The school's communication director, Barbara Wiers, said in a statement Wednesday evening that Vergara had attended the school since kindergarten.

West worked as a substitute teacher for three years before accepting a position as the school's substitute coordinator and an in-building substitute teacher, Wiers said.

'Our hearts are heavy with these losses,' Wiers wrote in an email to AP.

It is unclear whether any of the victims were specifically targeted in the attack.

But Lyndsay O'Connor, a mother of two survivors, suggested that the regular study hall teacher, who was not there due to a 'planned absence,' may have been Natalie's target - though her idea has not been verified by police.

'We don't know if her target was the original teacher or just the kids in the class. She would have had to walk by the door and the door was open,' O'Connor said. 

Rupnow had two handguns with her during the attack but only used one to carry it out, Barnes revealed Wednesday, noting that he does not know how the teenager obtained the weapons. 

'We may never know what she was thinking that day, but we will do our best to try to add or give as much information to our public as possible,' he said. 

Investigators don't know if anyone was targeted in the attack or if the attack had been planned in advance, the police chief added.

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

While Rupnow had two handguns, Barnes said he does not know how she obtained them and he declined to say who purchased them, citing the ongoing investigation.

Police have said they received a call at 10.57am Monday morning, and within three minutes, county sheriff's deputies had arrived at Abundant Life Christian School, which educates about 420 students. Local police arrived seconds later.

At 11.05am, they said that they'd found the shooter wounded and recovered the weapon. Rupnow was pronounced dead on the way to hospital.

Simultaneously, fire department workers got to the scene and began to care for the victims.

Police, with the assistance of the FBI, have been scouring online records and other resources, as well as speaking with the shooter's parents and classmates in an attempt to determine a motive for the shooting, Barnes said. 

Authorities raided the Rupnows' Wisconsin home after the tragedy, and the shooter's father has been reportedly compliant with the ongoing investigation. 

Investigators have been trying to figure out if the teen's parents, Jeff and Melissa, had any involvement or contributed to Natalie's actions.

Online court records show no criminal cases against her father, Jeffrey Rupnow, or her mother, Mellissa Rupnow. 

They are divorced and shared custody of their daughter, but she primarily lived with her father, according to court documents. Divorce records indicate that Rupnow was in therapy in 2022, but don't say why.

No decisions have been made about whether Rupnow's parents might be charged in relation to the shooting, Barnes said.

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

But the Wisconsin shooting stands out because school shootings by teenage females have been extremely rare in the US, with males in their teens and 20s carrying out the majority of them, said David Riedman, founder of the K-12 School Shooting Database.

Abundant Life is a nondenominational Christian school that offers prekindergarten classes through high school. About 420 students attend the institution.