INDIANAPOLIS — An Indianapolis man has been sentenced to life in prison without parole for killing three people over four days in attacks last spring that authorities say he justified by citing the horror movie “The Purge.”

A Marion County judge sentenced 20-year-old Johnathan Cruz to three consecutive life terms on Thursday.

Cruz pleaded guilty last month to three counts of murder. In exchange, prosecutors dropped plans to seek the death penalty.

Cruz was charged with fatally shooting three men during attacks on Indianapolis’ east and north sides.

Detectives say a witness told them Cruz confessed he’d been “purging” by shooting and robbing people, referring to the 2013 movie with a plot about violent crime, including murder, being legal one night each year.

Prosecutor Terry Curry says the attacks were “absolutely random.”