ALEXANDRIA, La. - A brother and sister face murder charges in the deaths of three people whose bodies were found in two separate locations in a central Louisiana parish, authorities said Thursday.

The siblings, 29-year-old Matthew Sonnier and 31-year-old Ebony Nicole Sonnier, were arrested on first-degree murder charges in the deaths of two Alexandria men whose burned bodies were found in Rapides Parish. Investigators discovered the remains of Kendrick Dwann Horn, 33, and Jeremy Deon Norris, 28, after extinguishing a fire in a roadside ditch last week.

The Sonniers also face first-degree murder charges in the fatal stabbing of 42-year-old Latish White, an Alexandria woman whose partially clothed body was found in a Pineville road approximately three hours before the discovery of the burned bodies. Police have described Matthew Sonnier as a "known acquaintance" of White.

Get Breaking News Delivered to Your Inbox

Rapides Parish Sheriff William Earl Hilton wouldn't immediately explain why investigators believe the cases are connected.

"I absolutely don't want to do anything that's going to cause a problem in the future for the prosecution," he said at a news conference.

The siblings, both of Alexandria, have been in police custody since Oct. 25. Matthew Sonnier initially was arrested on a second-degree murder charge in White's death, and his sister was arrested on drug charges, according to Pineville Deputy Police Chief Darrell Basco.

It wasn't immediately clear if either sibling has an attorney yet.

Hilton said the murder charges stem from a "very intense investigation" that led to hundreds of pieces of evidence collected at eight different locations.

"There are so many different tentacles to this thing that went so many different places," he said. "No one can remember this many different crime scenes that we had to process."