Las Vegas: The gunman in a deadly shooting at the University of Nevada, Las Vegas (UNLV), was a financially struggling academic, police said on Thursday.
The shooter, who died at the scene, killed three people on Wednesday and injured another.
Who was the gunman?
Police identified the perpetrator as Anthony James Polito. The 67-year-old had a list of targets at UNLV and East Carolina University in North Carolina, where he once taught.
He had applied for jobs at several educational institutions in the US state of Nevada, but was denied employment each time, authorities said.
Polito appeared to have sent 22 letters to various university personnel across the country with no return address, the police said.
Sheriff Kevin McMahill of the Las Vegas Metropolitan Police Department said authorities had managed to intercept the letters before they were delivered. A suspicious white powdery substance was found in at least one of them.
The UNLV shooting left at least three people dead before the suspect's death. All victims were faculty members but none of them were on the list of targets. A fourth individual, a 38-year-old visiting professor, was injured and his condition was downgraded to life-threatening on Thursday, police said.
UNLV President Keith E. Whitfield said that the shooting "was the most difficult day in the history of our university." He identified two of the victims as business school professors Patricia Navarro-Velez and Cha Jan "Jerry" Chang.
While the precise motive for the shooting had not been determined, officials said UNLV students did not appear to be the primary target of the attack. However, authorities noted that Polito had applied for several jobs at different colleges and universities in Nevada and was denied the job each time.
"We know he had applied numerous times for jobs with several Nevada higher education institutions," McMahill said, without specifying whether UNLV was one of them.
He added that police had uncovered evidence that Polito was struggling financially, citing an eviction notice on the door of his residence. He had a previous criminal record of computer trespass back in 1992 in Virginia.
This weekend the US logged its 37th and 38th mass shootings of the year, surpassing last year's grim record of 36. A mass shooting is defined as an incident in which four or more people are killed, not including the perpetrator.
At least 203 people have been killed in mass shootings in the US this year.
Las Vegas was also the site of one of the worst such incidents in US history when in 2017 a lone gunman in a 32nd-floor suite in the Mandalay Bay Casino killed 60 people and injured over 400 more when he shot more than 1,000 rounds at a crowd gathered at a country music festival below.