Matthew Dolloff, who is accused by police of fatally shooting Lee Keltner on Saturday, had been booked into a Denver jail on suspicion of first-degree murder.
The lesser charge will be filed in court on Monday, according to the office of DA Beth McCann.
Dolloff’s attorney, Doug Richards, did not immediately respond to CNN’s request for comment.
He has said that Dolloff acted in self-defense.
The images show Keltner arguing with another man, and witnesses thought the men were going to fight, the affidavit says.
Dolloff and another man become engaged in the confrontation, and Keltner is seen holding the can of pepper spray, according to the affidavit.
Keltner then turns his attention toward Dolloff and the other man, and the images show Keltner and Dolloff “face each other,” according to the affidavit.
“Mr. (Lee) Keltner strikes Mr. (Dolloff) in the side of the head with an open hand. Mr. (Dolloff) is then observed drawing a handgun from his waistband, aiming at Lee Keltner and shooting once, striking Mr. Keltner, as Mr. Keltner discharges his (pepper) spray,” the affidavit says.
Keltner died at a Denver hospital, the Medical Examiner’s Office said in a statement.
In a statement released Sunday, Pinkerton said Dolloff was a contractor from a third-party vendor.
Dolloff is not licensed to be a security guard in Denver, according to Eric Escudero, a spokesman for the city’s Department of Excise and Licenses.
If Dolloff was operating without a license, he could be fined up to $999 or face up to a year in jail, Escudero said. The company that hired Dolloff could also face administrative action if this were the case, according to Escudero.
Richards earlier this week told the Denver Post that Dolloff was defending himself.
In Colorado, second-degree murder carries a mandatory sentence of 16 to 48 years if found guilty.
CNN’s Kay Jones, Lucy Kavanov and Raja Razek contributed to this report.