Las Vegas police stand near the scene of a shooting at the University of Nevada, Las Vegas, Thursday, Dec. 7, 2023, in Las Vegas. (John Locher/AP)

(CNN) — Investigators searching for the motive of Anthony Polito, the gunman who killed 3 faculty members at the University of Nevada, Las Vegas on Wednesday, have uncovered a “target list” that included faculty at the university and elsewhere, according to Las Vegas Sheriff Kevin McMahill.

Polito, who was shot and killed by police, injured a fourth person during the shooting inside a UNLV business school building, authorities said. The victim, a visiting male professor, is being treated for life-threatening injuries, McMahill said Thursday.

The 67-year-old Polito had written a “target list” that included “people he was seeking on the university campus as well as faculty from the Eastern Carolina University,” McMahill said Thursday, though he noted none of the faculty members shot Wednesday were on the list.

McMahill did not explain what led investigators to believe it was a list of targets or where the document was found.

It is still unclear why Polito, who lived in the Las Vegas suburb of Henderson, targeted UNLV or if he had any connection to the school. He had worked at schools in Georgia and North Carolina, his now-removed LinkedIn page showed, including as a business professor at Eastern Carolina University. And in recent years he worked as an adjunct instructor at and attended Roseman University in Henderson, ending his association with the school in 2022, the school confirmed.

Polito had unsuccessfully applied to several higher education jobs in Nevada and appeared to be struggling financially, McMahill said Thursday, noting an eviction notice was found on the door of his Henderson apartment.

In the hours leading up to the shooting, Polito had mailed 22 letters to university personnel across the country with no return address, the sheriff said. At least some of the envelopes had a white powder in them, but the substance was found to be harmless, Las Vegas police said Thursday evening. Further details about the letters’ contents weren’t immediately released.

Detectives are working with the postal inspector and federal personnel to process the letters, but are asking people who work in academia who receive a letter with no return address to “proceed with caution,” McMahill said.

UNLV president Keith Whitfield described the shooting, which happened just days before the start of final exams, as “the most difficult day in the history of our university.”

The shooting began shortly before noon on Wednesday inside the university’s Beam Hall, where professors had been preparing students for the tests to come. Outside, a gathering of students was enjoying games, food and other activities.

Two of the people killed were business school professors Patricia Navarro-Velez and Cha-Jan “Jerry” Chang, the president said Thursday in a letter to the school community. The name of the third slain faculty member will be released after that person’s relatives are notified, he said.

“I won’t sugarcoat it. We are all hurting right now,” Whitfield said. “But it’s in these trying times that we need to lean on one another for support.”

UNLV mourns beloved faculty

In his letter to the university community, Whitfield acknowledged the shock many on campus are grappling with following the loss of several beloved faculty members.

“Words are still hard to come by as we’re only beginning to process the grief, loss, anger, and fear associated with Wednesday’s tragic campus shooting that took the lives of three of our cherished faculty members,” Whitfield wrote.

Navarro-Velez, an assistant professor of accounting, had been teaching at the school for almost five years and had “devoted her career to educating the next generation of accountants,” the president said.

The second slain professor, Chang, had been teaching UNLV’s business school students for more than 20 years as a “longtime educator of management information systems,” Whitfield said.

Navarro-Velez, 39, worked on the fourth floor of Beam Hall and Chang, 64, worked on the third floor, according to the sheriff.

Ammunition, electronics found at shooter’s home

Investigators found several computers and hard drive components were found while searching Polito’s apartment, the sheriff said Thursday.

Investigators are scrubbing the devices and scouring Polito’s social media in an effort to gain insight into any possible motive, he said.

Additionally, authorities discovered ammunition consistent with cartridges found at the scene of the shooting, as well as a Taurus box matching the handgun police believe the gunman used, he noted.

On a chair, investigators also discovered a document similar to a “last will and testament,” McMahill said.

Gunman was fascinated by Vegas and conspiracy theories

Polito’s online writings paint a picture of a man who was fascinated by Las Vegas and had an interest in various conspiracy theories.

His personal website includes a handful of syllabuses for his past courses but is largely a list of hundreds of links related to his personal interests entitled “Resources.” While the list includes ordinary topics like “Travel” and “Shopping,” one section is devoted to “Powerful Organizations Bent on Global Domination!”

It also includes links to common conspiracy theory fodder like Freemasonry, the Trilateral Commission and “The Rothchild (sic) Family.” George Soros, a common target for antisemitic conspiracy theories, is listed as one of the “Great Minds of the Twentieth Century,” alongside Albert Einstein and others.

Three of Polito’s former students say he spoke frequently about Las Vegas and visited the city as much as he could while teaching in other states. His website also notes he had made “more than two dozen trips to Vegas over the last fifteen years,” although it was not clear when the statement was originally posted.

Jonathan Peralta, who was in one of Polito’s classes at ECU in 2013 or 2014, told CNN Polito had an unorthodox teaching style and would usually start his classes with stories, frequently about Las Vegas.

“This was surprising,” Peralta said of the UNLV shooting. “The Vegas connection is what makes it so crazy because he would talk about Vegas so much.”

Polito worked at ECU’s college of business from 2001 until he resigned in 2017, when he was a tenured associate professor, a college spokesperson told CNN. He had ties to Nevada’s Roseman University from October 2018 to June 2022, attending the school and working as an adjunct professor, a school spokesperson said.

How the shooting unfolded

Authorities still are trying to piece together what happened inside Beam Hall, which does not have interior cameras, but have been able to construct a timeline of events before and after Polito entered the building, the sheriff said.

Polito arrived at the university just before 11:30 a.m. Wednesday, and police began receiving 911 calls around 11:45 a.m. about a shooting at the university, prompting both on- and off-duty law enforcement to rush to the campus, according to McMahill.

University and city police arrived on the scene and entered Beam Hall, where classrooms of students and professors were preparing for exams next week, the sheriff said. The first officer got to the scene within 78 seconds of the first 911 call, according to Adam Garcia, the director of university police services, southern command.

Polito, armed with a 9 mm pistol and nine loaded magazines, made his way through multiple floors of the building before exiting around 11:55 a.m., the sheriff said. Outside, he confronted university police and a shootout ensued, McMahill said.

Polito was shot multiple times and collapsed, McMahill said. He was then arrested and died at the scene, he added.

“Officers then assembled action teams and began a systematic search for additional suspects and victims. Those teams went through multiple buildings and multiple floors. Many times we had to force entry into rooms where students and faculty were sheltering in place,” sheriff said.

The fear and panic on campus evoked memories of the Route 91 Harvest music festival massacre, which took place near UNLV on October 1, 2017, and remains the deadliest mass shooting in modern US history. Wednesday’s tragedy marked the 80th school shooting in the US so far this year, 29 of which have been on university and college campuses, according to a CNN analysis.