Rex Heuermann, the prime suspect in the Gilgo Beach serial murders, now faces six counts of murder following the addition of two new charges. The Prosecutor's Office also revealed the existence of a disturbing “planning document” for the murders.

This Thursday, the 60-year-old former architect appeared before Suffolk County Superior Court Judge Timothy Mazzei to formally face two new charges of second-degree murder for the deaths of Jessica Taylor and Sandra Costilla.

During the hearing, the Prosecutor's Office also revealed the existence of a disturbing Microsoft Word document that was found on the suspect's laptop. The document titled "HK2002-04," was created in 2000 and edited throughout 2002, which allegedly details specific aspects of the murders.

The file included sections such as "problems," detailing possible evidence such as DNA, tire marks, and blood stains; as well as another section called "supplies," which listed items such as ropes, tarps, and duct tape; "DS," possibly referring to evidence disposal sites; and "TRG," which specified the type of victims sought.

The document also detailed steps to follow after the murders, including body preparation and evidence disposal, as well as reminders for future actions, such as the importance of rest and proper tool selection.

"The task force believes this is a planning document that was utilized by Heuermann to methodically blueprint and plan out his kills with excruciating detail," Suffolk County District Attorney Raymond Tierney said Thursday.

Heuermann's arrest occurred on July 13, 2023 in New York City, after more than a decade of investigation that has not ended. Initially, the accusations focused on the homicides of Megan Waterman, 22 years old; Melissa Barthelemy, 24; and Amber Lynn Costello, 27, whose bodies were found on Long Island in 2010.

However, earlier this year prosecutors added a new charge for the murder of Maureen Brainard-Barnes, 25 years old, and now, the list of accusations is expanded even further with the inclusion of Jessica Taylor, 20 years old, and Sandra Costilla, who was murdered in 1993 and had not previously been linked to the Gilgo Beach crimes.