The vast manhunt for the shooter who killed rightwing activist Charlie Kirk stretched into a third day on Friday, after police released fresh images in an effort to crack a case that has raised tensions in the United States.

The gunman fired a single, fatal shot at Kirk — a 31-year-old who rallied youth support for U.S. President Donald Trump — during an appearance at a Utah university on Wednesday.

Despite hundreds of agents from across 20 law enforcement agencies working the case, investigators appealed for the public's help on Thursday and unveiled new images of a man they want to question.