Kirk, a close ally of US President Donald Trump, was shot dead last week during a speaking event on a Utah university campus. He was the founder of the influential conservative youth political group Turning Point USA.
Authorities said 22-year-old Tyler Robinson used a rifle to shoot Kirk with a single bullet to the neck from a rooftop. He was arrested after a 33-hour manhunt.
“After reviewing the evidence that law enforcement has collected thus far, I am… charging Tyler James Robinson, age 22, with the following crimes,” Utah County attorney Jeff Gray told a press conference.
“Count one, aggravated murder, a capital offence, for intentionally or knowingly causing the death of Charlie Kirk under circumstances that created a great risk of death to others.”
Six other charges include obstruction of justice and witness tampering, allegedly for ordering his room-mate to stay silent.
“I am filing a notice of intent to seek the death penalty,” Gray added.
“I do not take this decision lightly, and it is a decision I have made independently as county attorney based solely on the available evidence and circumstances and nature of the crime.”
Gray cited lengthy text message exchanges between Robinson and his room-mate, whom he described as “a biological male who was transitioning genders.”
Robinson and the room-mate were in a romantic relationship, Gray said.
In one part of the exchange, the room-mate, who was not named, asked Robinson why he had killed Kirk.
“‘I had enough of his hatred.'” Gray cited the messages as saying. “‘Some hate can’t be negotiated out.'”
Robinson, who is being held without bail, was expected to make an initial court appearance later on Tuesday.
Gray explained that in line with practice in the county, this appearance would be by video link.
Kirk, a father of two, used his audiences on TikTok, Instagram and YouTube to build support for conservative talking points, including strong criticism of the transgender rights movement.
A polarising figure, he often posted edited clips of his interactions during debates at his many college events. (AFP)
