The fatal shootings of three Muslim-American college students in North Carolina has sparked global outrage as the Islamic community and supporters demand that their murders be investigated as a hate crime.

The tragedy occurred Tuesday evening near the campus of the University of North Carolina at Chapel Hill when 23-year-old Deah Shaddy Barakat, his 21-year-old wife Yusor Mohammad and her 19-year-old sister Razan Mohammad Abu-Salha were gunned down by a neighbor. The suspect, 46-year-old suspect Craig Stephen Hicks, has been charged with murder.

The suspect's wife, Karen Hicks, claims that her husband killed the students over an ongoing parking space dispute.

"This incident had nothing to do with religion or the victims' faith, but in fact was related to the longstanding parking disputes that my husband had with the neighbors," said Karen during a news conference on Wednesday, according to CNN.

Rob Maitland, an attorney representing Karen, who was in the process of getting a divorce from her husband, alluded that mental illness was a contributing factor in the shooting. The shooting "highlights the importance of access to mental health care services," he said.

However, family members say that the victims had expressed fear of living next to the man because of their faith. According to them, the newlywed Hicks couple began to feel threatened after Mohammad, who wore a hijab, moved into Karen's new husband's apartment.

"We have no doubt that the way they looked and the way they believed had something to do with this," said Mohammad Abu-Salha, the father of the female victims. "My daughter, Yusor, honest to God, told us on more than two occasions that this man came knocking at the door and fighting about everything with a gun on his belt, more than twice. She told us, 'Daddy, I think he hates us for who we are and how we look.'"

He added that their murders should be treated as a hate crime.

"Now that we know from the police that they were shot in the head, very quickly, the three of them, one bullet each, in a very small space inside in the apartment. That's execution-style. I don't know, if that is not hate, what that would be," Mohammad Abu-Salha said.

Since the attack, the hashtags #MuslimLivesMatter and #ChapelHillShooting have been a top trending topic on Twitter across the world.

All three victims were born in the United States and grew up in the area.

Barakat, a second-year dental student at the UNC, and Yusor Mohammad were married in late December. According to a Facebook page, the couple traveled to Turkey last year to provide free dental care to students.

"He was a completely genuine guy. Loving, caring, friendly, smart. He was an ideal human being. He was a role model," said Muneeb Mustafa, who attended the same Raleigh mosque as Barakat.

The Council on American-Islamic Relations have also called for police to "address speculation about a possible bias motive," while the Muslim Public Affairs Council is requesting a federal investigation "if the motives of the shooter are confirmed based on his previous social media posts."