Utah investigators sought help from the public on Wednesday as they work to unravel who was at fault when a safety volunteer at a “No Kings” rally fired at an alleged gunman and inadvertently hit and killed a protester.

The alleged rifleman, Arturo Gamboa, 24, was also shot and was taken into custody on a murder charge, Salt Lake City Police Chief Brian Redd said at a Sunday news conference. The bystander who was killed was identified as Arthur Folasa Ah Loo, 39, a fashion designer from Samoa.

Arthur Folasa Ah Loo, 39, a Samoan-born fashion designer, was participating in an anti-Trump protest in Salt Lake City on Saturday when he was shot by a man working security, the police said.