CHAPEL HILL, N.C. — Police are trying to determine whether hate played any role in the killing of three Muslims, a crime they said was sparked by a neighbor’s long-simmering anger over parking and noise inside their condominium complex.

Craig Stephen Hicks, 46, describes himself as a “gun-toting” atheist. Neighbors say he always seemed angry and confrontational. His ex-wife said he was obsessed with the shooting-rampage movie “Falling Down” and showed “no compassion at all” for other people.

His current wife, Karen Hicks, said he “champions the rights of others” and that the killings “had nothing do with religion or the victims’ faith.” She issued another statement later Wednesday, saying she’s divorcing him.

Hicks appeared in court Wednesday on charges of first-degree murder in the deaths Tuesday of Deah Shaddy Barakat, 23, his wife, Yusor Mohammad, 21, and her sister Razan Mohammad Abu-Salha, 19. He pleaded indigence and was appointed a public defender.

On Tuesday, officers were summoned by a neighbor who called 911 to report 5 to 10 gunshots and the sound of people screaming. The women’s father, Mohammad Abu-Salha, said police told him each was shot in the head inside the couple’s apartment, and that he, for one, is convinced it was a hate crime.

“The media here bombards the American citizen with Islamic, Islamic, Islamic terrorism and makes people here scared of us and hate us and want us out. So if somebody has any conflict with you, and they already hate you, you get a bullet in the head,” said Abu-Salha, who is a psychiatrist.

The killings fueled outrage among people who blame anti-Muslim rhetoric for hate crimes. A Muslim advocacy organization pressed authorities to investigate possible religious bias. Many posted social media updates with the hashtags #MuslimLivesMatter.

“We understand the concerns about the possibility that this was hate-motivated, and we will exhaust every lead to determine if that is the case,” Chapel Hill Police Chief Chris Blue said in an email.

Barakat and Mohammad were newlyweds who helped the homeless and raised funds to help Syrian refugees in Turkey this summer. They met while running the Muslim Student Association at N.C. State before he began pursuing an advanced degree in dentistry at the University of North Carolina at Chapel Hill. Mohammad planned to join her husband in dentistry school in the fall.

Abu-Salha was visiting them Tuesday from Raleigh, where she was majoring in design at N.C. State.

Hicks, an unemployed Second Amendment rights advocate with a concealed weapons permit, often complained about both Christians and Muslims on his Facebook page. “Some call me a gun-toting Liberal, others call me an open-minded Conservative,” Hicks wrote.

Imad Ahmad, who lived in the condo where his friends were killed until Barakat and Mohammed were married in December, said Hicks complained about once a month that the two men were parking in a visitor’s space as well as their assigned spot.

“He would come over to the door, knock on the door and then have a gun on his hip saying ‘You guys need to not park here,’ ” said Ahmad, a graduate student in chemistry at UNC-Chapel Hill. “He did it again after they got married.”

Both Hicks and his neighbors complained to the property managers, who apparently didn’t intervene. “They told us to call the police if the guy came and harassed us again,” Ahmad said.

“This man was frustrated day in and day out about not being able to park where he wanted to,” said Karen Hicks’ attorney, Robert Maitland.

Hicks’ ex-wife, Cynthia Hurley, said that before they divorced about 17 years ago, his favorite movie was “Falling Down,” the 1993 Michael Douglas film about a divorced unemployed engineer who goes on a shooting rampage.

“That always freaked me out,” Hurley said. “He watched it incessantly. He thought it was hilarious. He had no compassion at all.”