The 46-year-old man suspected of shooting three Muslim students belonging to the University of North Carolina was active online in criticising all forms of religion, police say.

The Independent reported that the man, who was identified as Craig Stephen Hicks, identified himself as "anti-theist" in his social media accounts and supported atheist organisations.

In addition, a Facebook page in his name surfaced with more information about the alleged shooter. The page said that Hicks had read paralegal studies in Durham Technical Community College, and that he had pledged his support for the group "Atheists for Equality."

Before the shooting, Hicks had re-posted an image from the United Atheists of America. This image had questioned the conflict between the Muslims and the Christians despite their apparent agreement on "many ideological issues."

According to the Independent, Hicks was also a fan of the Atheist Experience, Criminal Minds and Friends, as well as Thomas Paine's The Age of Reason and Richard Dawkins' The God Delusion.

Dawkins was among those condemning the shooting. "How could any decent person NOT condemn the vile murder of three young US Muslims in Chapel Hill?" Dawkins said in his Twitter account.

Hicks turned himself in to Chapel Hill police on Wednesday for the murder of Deah Shaddy Barakat, his wife, Yusor Mohammad Abu-Salha, and her sister, Razan Mohammad Abu-Salha. They were killed in their apartment complex on Summerwalk Circle in Chapel Hill.

Police responded to reports of a shooting in the area at 5:11pm Wednesday, and found the three victims dead on the scene. The investigators later issued a statement that said they think the crime was "motivated by an ongoing neighbour dispute over parking."

However, the father of the women said told The Independent that the shooting was a "hate crime." He also revealed that Hicks had targeted his daughter Yusor and her husband Deah a "couple of times."