A federal investigation into Tyler Robinson, the suspect arrested in the assassination of conservative political activist Charlie Kirk, has reportedly has no link to left-wing groups, three sources with knowledge of the situation confirmed to NBC News.

“Thus far, there is no evidence connecting the suspect with any left-wing groups," one source said. “Every indication so far is that this was one guy who did one really bad thing because he found Kirk’s ideology personally offensive."

President Donald Trump and his administration have pledged to crack down on left-wing groups that they presumed to be linked to Robinson, 22, following Kirk's shooting. The president announced he planned to designate Antifa as a "major terrorist organization" in a post shared on his Truth Social account.

Last week, text messages sent by the Robinson to his roommate, whom police described as "a biological male" transitioning to female and "involved in a romantic relationship" with the suspect, who he referred to as "my love," were revealed.

“Drop what you are doing, look under my keyboard,” Robinson wrote, according to court papers filed by Utah County Attorney Jeff Gray on Tuesday (September 16).

The roommate found a note written by Robinson that allegedly stated, "I had the opportunity to take out Charlie Kirk and I'm going to take it."

Robinson's parents, who were reported to be conservative, began to suspect he was the shooter after a surveillance photo was shared publicly during the manhunt that preceded his arrest. The suspect claimed the murder weapon was a gift from his grandfather.

“My dad wants photos of the rifle,” Robinson wrote, according to charging document released on Tuesday. “He's calling me rn, not answering.”

Robinson also told the roommate to "delete this exchange," which they didn't comply to and the thread became evidence used to charge Robinson with aggravated murder in connection to Kirk's death. The 22-year-old was also charged with felony discharge of a firearm, obstruction of justice, witness tampering and several other counts, while officials have publicly stated their intention to seek the death penalty.

Kirk, 31, was fatally shot in the neck during what was scheduled to be the first stop on his 'American Comeback Tour' at Utah Valley University last Wednesday (September 10). Robinson was publicly identified by police following his arrest last Friday (September 12).

Kirk founded Turning Point USA, a conservative youth organization, at the age of 18 along with tea party activist William Montgomery in 2012. The political pundit gained notoriety debating liberal students, winning over conservative financiers.

Kirk enthusiastically supported President Trump during his 2016 presidential campaign and served as a personal aide to his son, Donald Trump Jr., during the campaign, while also gaining a regular presence on cable news.