Gilgo Suspect’s How-To Manual Reflects a Killer’s Mind, Prosecutors Say

When prosecutors indicted Rex Heuermann this month on two additional murders in the Gilgo Beach serial killings on Long Island, they also described a manual he kept as a “planning document.”

Prosecutors say Mr. Heuermann created the document to “methodically blueprint” the selection, killing and disposal of victims, according to a bail application filed with the indictment.

Written in capital letters, the manual is structured as a series of reminder lists under topics like PRE-PREP, which offers banal tips about the importance of checking weather reports and looking for surveillance cameras. The PREP section is more grim, with directives to set up a holding area and “stage” with equipment for apparent sexual torture. The BODY PREP list includes reminders on how to avoid leaving evidence.

The manual is the most informative piece of narrative evidence disclosed since prosecutors filed legal papers after Mr. Heuermann’s arrest detailing investigators’ 18-month pursuit. In prosecutors’ hands, a document they say the defendant created to avoid detection may instead become damning evidence against him, even given the already disclosed DNA matches, phone records and internet activity that prosecutors say tie Mr. Heuermann to the killings.

The methods that Mr. Heuermann outlined in the document in “excruciating detail” correspond to the ways in which he carried out the six murders, said the Suffolk County district attorney, Raymond A. Tierney, adding that Mr. Heuermann’s “intent was specifically to locate these victims, to hunt them down, to bring them under his control and to kill them.”

Mr. Heuermann, a 60-year-old architect, was arrested last summer and later charged with murdering the so-called Gilgo Four. Those victims were among 10 sets of human remains found along a desolate stretch of Ocean Parkway east of Jones Beach in 2010 and 2011.

He has pleaded not guilty to all six murders and has remained in jail as he awaits trial.

Legal experts agreed that the newly disclosed document was devastating for Mr. Heuermann.

“It is a road map for conviction,” said Stephen Scaring, a criminal defense lawyer on Long Island and a former chief of homicide for the Nassau County district attorney’s office.

Mr. Tierney said the manual’s instructions on “packaging” bodies for transport corresponded to the condition of the Gilgo Four when they were found near Ocean Parkway. The instructions also match, he said, the handling of the bodies of the two women that Mr. Heuermann was charged this month with killing.

One, Sandra Costilla, a 28-year-old Queens woman, was found mutilated in the woods in Southampton in 1993. The other, Jessica Taylor, was dismembered, with some of her remains found near Gilgo Beach in 2011 and then linked to others that had been found eight years earlier in a remote wooded area in Manorville, a 45-minute drive east.

Prosecutors say the document, which Mr. Heuermann created in 2000 and modified through 2002, was on a computer hard drive that investigators seized from his basement during an extensive search after his arrest last summer.

The manual, assembled with an architect’s precision, suggests that Mr. Heuermann engaged in sadistic sexual acts with his victims before and after death.

It arms prosecutors with a strong argument that Mr. Heuermann maintained a double life, waiting for his wife and their children to leave on vacation, and then possibly detaining, torturing and killing his victims in the basement of the family home in Massapequa Park, a middle-class neighborhood dense with well-kept houses.

“This document is a killer. It’s better than a written or even videotaped confession because with those, any good lawyer on cross-examination can create issues of doubt,” said William Keahon, a Long Island defense lawyer and former chief of the homicide division in the Suffolk County district attorney’s office.

“But how do you cross-examine a document he created himself on his computer?” he said.

Michael Brown, Mr. Heuermann’s normally unflappable defense lawyer, has consistently found ways to parry a steady stream of damning details since his client’s arrest. But the news of the manual, released just before his client was indicted, left him scrambling for answers to reporters’ questions about a document in which his client calls the search for a victim a “hunt” and engaging with their bodies “play time.”

In a phone interview, Mr. Brown questioned the document’s authorship and whether prosecutors might have taken it out of context, but said he needed more time to review it.

Mr. Brown did call the two new charges, and the manual’s notes on mutilation and dismemberment, “inconsistent with the initial theory” put forth by prosecutors regarding the Gilgo Four. Unlike Ms. Taylor and Ms. Costilla, those four victims were all killed within several years of their discovery in 2010 and dumped close together, their bodies intact.

Mr. Scaring said that a defense lawyer in this situation could try swinging the strength of the opposing case to his advantage by arguing that his client was being framed and that “no case can be this strong and have gone unresolved for so many years.”

Prosecutors did not release the planning document itself, but rather included images of its lists and reminders.

The manual includes a reminder to “DISTROY COMPUTER FILES,” and Mr. Heuermann had taken steps to delete it, prosecutors said. But forensics experts were able to recover it in March, prosecutors said, and its content prompted a new flurry of searches, including of his home in Massapequa Park.

Investigators had already scoured the home after Mr. Heuermann’s arrest last summer. But they returned in May with an infrared light and spent six days searching the paneled walls and dropped ceiling of the basement for signs that Mr. Heuermann may have used tape and pushpins to hang dropcloths to conceal violent acts, as suggested in the manual.

The document also prompted a nine-day search by dogs in the woods in Manorville, where Ms. Taylor’s body was found, and in Southampton for more clues regarding Ms. Costilla.

Prosecutors said Mr. Heuermann mutilated a tattoo on Ms. Taylor’s right hip to try to obscure her identity, a tactic the document recommends in its BODY PREP section.

Ms. Costilla’s death stands, for now, as the earliest killing that Mr. Heuermann has been charged with. Her 1993 death came shortly after his mother and a former companion of his moved out of the Massapequa Park house where he had lived his entire life.

Ms. Costilla’s long-unsolved murder had not previously been associated with the Gilgo Beach investigation, and her involvement suggests that Mr. Heuermann might be tied to murders outside the Gilgo case.

At a news conference after the indictments this month, Mr. Tierney said the investigation would continue as long as clues kept emerging.

While mostly containing general notes and reminders, the document also makes some specific references to possible victims and crime scenes, including a woman’s phone numbers and tallies of surveillance cameras on the Long Island Expressway.

A section on dump sites mentions Mill Road, which prosecutors say lies in an area in Manorville near where investigators found partial remains of Ms. Taylor as well as those of Valerie Mack, who went missing in 2000. Additional remains of Ms. Mack were found near Gilgo Beach in 2011, where remains of Ms. Taylor had also been found, and the manual’s reference to Mill Road has led prosecutors to call Mr. Heuermann a prime suspect in her death, Mr. Tierney said.

While not a manifesto, the document is nevertheless revelatory about Mr. Heuermann’s personality, said Scott Bonn, a criminologist and expert on serial killers. “It’s totally consistent with his personality type,” he said. “He’s a highly meticulous, organized, intelligent individual who didn’t leave one detail unattended to.”

“For him, it’s all about the planning and the details. As an architect, he is meticulous about the detail in his work and in his killing,” Mr. Bonn said. “Just like he’d create a blueprint for a building, he had a blueprint for murder.”