Craig Stephen Hicks' motive for shooting and killing three young American Muslims in Chapel Hill, N.C. is being called into question, but the victims' family members are maintaining it was a hate crime.

According to Fox News, police disclosed Hicks, 46, shot and killed Deah Barakat, 23; his wife, Yusor Abu-Salha, 21; and her sister, Razan Abu-Salha, 19, over a parking spot. Hicks identifies as an atheist on his Facebook page, but also has posted several messages and photos mocking and criticizing organized religion.

Dr. Mohammad Abu-Salha, Yusor and Razan's father, told the Raleigh News and Observer Hicks acted out of hate. He said his daughter had previously mentioned having "a hateful neighbor."

"It was execution style, a bullet in every head," he said. "This was not a dispute over a parking space; this was a hate crime. This man had picked on my daughter and her husband a couple of times before, and he talked with them with his gun in his belt. And they were uncomfortable with him, but they did not know he would go this far.

"Honest to God, she said, 'He hates us for what we are and how we look.'"

Barakat was a second-year student at the University of North Carolina (UNC) - Chapel Hill School of Dentistry, a program his wife was going to start in the fall. Razan was an undergraduate at North Carolina State University, but all three were living together in Chapel Hill.

Michael Nam, another resident who lives in the apartment complex, which is home to some students, told BBC News he had clashed with Hicks over a parking spot. Nam, a local pharmacy technician, said Hicks confronted him on one occasion with his gun on his hip. The UNC graduate said he relented and moved his car more out of annoyance than fear.

Police responded to a 911 call Tuesday evening for reports of gunshots. The caller told the Observer she thinks she heard "about eight shots go off" while she was walking through a hallway at the apartment complex. During the initial shots there was screaming, but then it went quiet, at which time she heard three final gunshots.

Hicks fled the scene and turned himself in later Tuesday night. Hicks' wife Karen said the dispute was over a parking spot and nothing more.

"I can say that it is my absolute belief that this incident had nothing to do with religion or the victims' faith, but in fact was related to long-standing parking disputes my husband had with various (neighbors) regardless of their race, religion or creed," she said in a statement.

Hicks was charged with three counts of first-degree murder, but authorities have not said whether or not they will pursue the case as a hate crime.