RALEIGH, N.C. — The fathers of three young Muslims allegedly slain by a neighbor who was angry over parking spots stood before their caskets Thursday and urged a crowd of thousands to protect others by demanding justice.

More than 5,000 people came to the funeral of Deah Shaddy Barakat, 23; his wife, Yusor Mohammad Abu-Salha, 21; and her sister Razan Mohammad Abu-Salha, 19, who were killed Tuesday in the couple’s Chapel Hill apartment.

A self-described “gun toting” atheist with a reputation for bullying his neighbors, Craig Stephen Hicks, turned himself in and was jailed on first-degree murder charges.

Chapel Hill police said they are investigating whether religious or ethnic hatred motivated Hicks in any way, and federal investigators said hate crimes haven’t been ruled out. The FBI also announced Thursday that it has “opened a parallel preliminary inquiry to determine whether any federal laws were violated.”

U.S. Attorney Ripley Rand, the district’s top federal prosecutor, had said Wednesday that there was no immediate evidence Muslims were being targeted.

And that didn’t sit well with many at the funeral, where the victims were hailed as martyrs for their faith.

“When we say this was a hate crime it is all about protecting all other children in the USA,” Dr. Mohammad Yousif Abu-Salha, who lost his daughters, told the crowd. “It’s all about making this country that they loved, where they lived and died, peaceful for everybody else.”

“We need to identify things the way they really are,” Abu-Salha continued. “If somebody picks up a fight about anything they can invent, and they murder three people execution-style, we know what this is about. And they have posted on their Facebook how much they hated faith, there’s no doubt.”