Sickening details of planning documents of suspected serial killer read out in court during trial over murders

A New York architect previously accused of killing four women and leaving their corpses scattered along a coastal highway has been charged over the deaths of two more women.

Rex Heuermann, 60, appeared before a judge to face charges that he killed Jessica Taylor and Sandra Costilla, two young women who were long suspected of being the victims of men preying on sex workers.

Ms Taylor disappeared in 2003 and Ms Costilla was killed in 1993.

The new charges came days after police finished extensive searches of Heuermann’s Massapequa Park home and a wooded area on Long Island tied to the investigation of a string of deaths known as the Gilgo Beach serial killings.

In a court filing, prosecutors said new forensic testing methods had matched hairs found on or near both victims to a DNA profile that is a likely match to Heuermann.

The charges involving Ms Costilla, who was killed 30 years ago, indicate that prosecutors believe Heuermann was killing victims for much longer than previously thought.

Prosecutors also say they discovered a 'planning document' on the hard drive found in his basement used to 'methodically blueprint' his killings.

350 of Heuermann devices were recovered by investigators, with one having the sickening document on.

Rex Heuermann is now facing six murder charges (James Carbone/Newsday RM via Getty Images)

The document includes Heuermann’s concerns about leaving forensic evidence, guidance for cleaning and washing bodies, and notes on how to improve 'next time' such as hitting his victims in the face or neck instead.

He also allegedly wrote about the importance of sleep to avoid any 'problems' but also increase 'play time', ABC News reported.

Elsewhere, Huermann reportedly wrote in a post-murder checklist to do things such as 'burn gloves' and 'dispose of pics'.

Part of the disturbing document was read out in court today (Thursday, June 6).

Since late 2010, police have been investigating the deaths of at least 10 people — mostly female sex workers — whose remains were discovered along an isolated highway not far from Gilgo Beach on Long Island’s south shore.

Heuermann reportedly made a 'check list'. (Suffolk County District Attorney)

The victims had disappeared over a span of at least 14 years, and police made only halting progress in identifying possible suspects. Investigators long said it was likely that not all of the deaths were the work of the same killer.

Some of the victims disappeared in the mid-1990s, and investigators concluded that an 11th person who disappeared in 2010 from the barrier island community of Oak Beach had accidentally drowned.

Heuermann, who lived across a bay from where the bodies were found, was arrested last July.

He has been in custody since his arrest and has pleaded not guilty to the first four charges. He has also pleaded not guilty to the two new charges.