Rex Heuermann, the suspect in the Gilgo Beach killings, is expected to be indicted Thursday on new murder charges in the killings of two additional women, multiple law enforcement sources tell CNN.

The former New York architect was taken into custody last July and has already been charged with murder in the deaths of four women who have come to be known as the “Gilgo Four.”

Law enforcement officials say the murder charges are related two additional victims, Jessica Taylor and Valerie Mack, and come from a sweeping expansion of the investigation into Heuermann following his arrest last summer.

Heuermann’s arrest kicked off a media frenzy, with many wondering whether police had finally caught what the Gilgo Beach community had long feared was a serial killer responsible for a string of unsolved killings that took place over decades.