CEDAR RAPIDS, Iowa (AP) — The only survivor of a metal pipe attack in Iowa has died, prompting authorities to charge the suspect with a fourth count of first-degree murder.

The Linn County Sheriff’s Department alleges 34-year-old Luke Truesdell, of Marion, attacked four people with a metal pipe last week at a rural Iowa home near Cedar Rapids. Three people died at the home. The fourth person, 34-year-old Brent Anthony Brown, died two days later, Sheriff Brian Gardner said in a Sunday statement.

Truesdell’s public defender didn’t immediately respond to a request for comment from The Associated Press on Monday.

Authorities were still investigating what led to the attack, but Gardner has said that among the possible motives was that the crime might be made into a movie. He did not elaborate.

Gardner identified the others who were killed as 44-year-old Romondus Lamar Cooper of Cedar Rapids, 26-year-old Keonna Victoria Ryan of Cedar Rapids, and 33-year-old Amanda Sue Parker of Vinton.