The FBI says it's launching an inquiry parallel to a police homicide investigation as families demand a federal hate-crime investigation of three young Muslims allegedly slain by a North Carolina neighbor.

Muslim groups plan to press federal authorities for a hate-crime investigation by holding Friday prayers in front of the White House.

The FBI's main North Carolina office said Thursday its preliminary inquiry seeks "to determine whether or not any federal laws were violated." The FBI says it's also continuing to help police in the college town of Chapel Hill process evidence.

Craig Stephen Hicks has been jailed on first-degree murder charges in the deaths.

The father of 21-year-old Yusor Abu-Salha and her sister, 19-year-old Razan Abu-Salha, says the neighbor killed them because they were Muslims. They were killed along with Yusor's husband, Deah Barakat.