Three University of Nevada, Las Vegas faculty members died this week and another was critically injured when a lone gunman walked onto campus and opened fire in the building housing the business school.

The shooting stoked fear on the 30,000-student campus just miles from the Las Vegas Strip where the deadliest mass shooting in modern U.S. history led to the deaths of 60 people on Oct. 1, 2017.

Las Vegas police are still trying to understand what led Anthony Polito, a longtime business professor in North Carolina, to the campus on Wednesday. 6.

Here’s what we know:

THE GUNMAN

Anthony James Polito, 67, was a tenured associate professor who left East Carolina University in Greenville, North Carolina, in 2017 after teaching business there for more than 15 years.

After that, he taught courses between October 2018 and June 2022 at Roseman University of Health Sciences, a 1,000-student private college in suburban Henderson, Nevada. The job ended when the program he taught under was discontinued.

Polito legally bought a 9 mm handgun last year, Clark County Sheriff Kevin McMahill said, and had nine ammunition magazines holding more than 150 bullets with him when he was shot and killed by UNLV police outside the business school.

McMahill characterized Polito as “struggling financially,” but he didn’t elaborate other than to say Polito had an eviction noticed taped to his apartment door in Henderson.

WHAT HAPPENED THE DAY OF THE SHOOTING

Polito stopped by a post office to mail some letters before arriving at the UNLV campus before noon, McMahill said. He parked near the business school, stuffed ammunition in his waistbelt and went inside, authorities said.

Polito roamed the building and shot four faculty members before exiting and being confronted by plainclothes university officers who killed him in a shootout, authorities said.

McMahill said Thursday it was unclear where Polito fired the first shots that were reported at 11:45 a.m. or how many rounds were fired.

Based on the extra ammunition that Polito had, McMahill said more people might have been shot if not for the police response.

THE LIST AND LETTERS

Polito mailed 22 letters with no return address to university personnel across the country, McMahill said. A white powder found in one of the envelopes was not harmful, the sheriff said.

Polito also had a “target list” with the names of faculty members from UNLV and East Carolina University with him when he carried out the shooting, but none of the shooting victims’ names were on it, the sheriff said.

At Polito’s apartment, police found a chair with an arrow pointing to a document that McMahill described as “similar to a last will and testament.” The contents of that note were not disclosed.

THE VICTIMS

All four shooting victims were professors, including a 38-year-old visiting professor who remains hospitalized with life-threatening injuries, authorities said.

Killed were:

— Naoko Takemaru, 69, an associate professor of Japanese studies and author who oversaw the university’s Japanese Studies Program and received the William Morris Award for Excellence in Teaching from the College of Liberal Arts at UNLV.

— Cha Jan “Jerry” Chang, 64, an associate professor in the business school’s Management, Entrepreneurship & Technology department. He held degrees from Taiwan, Central Michigan University and Texas A&M University, according to his online resume, and he earned a Ph.D. in management information systems from the University of Pittsburgh.

— Patricia Navarro Velez, 39, an accounting professor with a Ph.D. in accounting who was focused on research in cybersecurity disclosures and data analytics, according to the school’s website.

WHAT’S NEXT FOR UNLV?

Final exams and the last week of in-person classes this semester have been canceled. University President Keith Whitfield told students and staff on Friday that students’ final grades will be based on work completed before the shooting Wednesday.

He cited the loss of the faculty members and the physical and emotional trauma the university has endured.

“What our university has endured on Dec. 6 is nothing short of life-changing. We will not ever forget that day,” he said at a news conference late Friday.

Whitfield set a Dec. 18 deadline for students to take optional, online final exams or complete take-home tests to improve their grades. Commencement ceremonies are still scheduled for Dec. 19-20.

The five-story building where the shooting happened remained closed Friday.