EXCLUSIVE: Shortly before New York police made a surprise return to the Long Island home of suspected serial killer Rex Heuermann, his family was still in possession of a gruesome album of crime scene photos, according to a source with knowledge of the incident.

The book, "Death Scenes: A Homicide Detective’s Scrapbook," is a collection of "strange and gruesome" crime scene photos taken by California detective Jack Huddleston and was allegedly spotted on a kitchen table in the home where Heuermann's estranged wife, Asa Ellerup, lives with their two adult children.

Ellerup’s lawyer, Bob Macedonio, said he had no knowledge of the book.

SUSPECTED SERIAL KILLER REX HEUERMANN'S HOME SEARCHED AGAIN

Alleged Gilgo serial killer Rex Heuermann appears inside Judge Tim Mazzei’s courtroom

Alleged Gilgo serial killer Rex Heuermann appears inside Judge Tim Mazzei’s courtroom in Suffolk County, New York on Tuesday, February 6, 2024. Heuermann is accused of killing four women whose remains were found in Gilgo Beach in 2010. (James Carbone/Newsday via Pool )

The source said it had been inventoried by detectives during the initial search of Heuermann’s home and returned to his family.

Investigators have said that Heuermann frequently searched the internet for gruesome images.

They allegedly found dozens of search terms – including "torture redhead porn," "girl with face beat up," "chubby 10 year old girl crying," and "Asian twink tied up" – on a burner phone and email account they seized under the fake name "Thomas Hawk." They also found more than 200 searches regarding other known serial killers and the Gilgo Beach case itself.

Police outside of a suburban home

Police serve a search warrant at the home of Rex Heuermann in Massapequa Park on Long Island, New York, on Monday, May 20, 2024. Investigators set up tents in the suspect's driveway and across the street, as vehicles from multiple law enforcement agencies, including state police and Suffolk County, lined the street. (Kevin C. Downs for Fox News Digital)

It’s unclear why police returned to Heuermann’s home Monday after spending almost two weeks investigating the building following his arrest in connection with three cold case murders in July. He was later charged with a fourth woman’s death in the "Gilgo Four" case — where four women’s remains were discovered next to Gilgo Beach on Ocean Parkway, about 20 minutes from Heuermann’s Massapequa Park home, on a sparsely populated stretch of highway.

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The Suffolk County District Attorney’s Office declined to comment on the photo booklet and has said it has a policy against commenting on an active investigation.

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Asa Ellerup and daughter Victoria Heuermann departs the Suffolk County Courthouse

Rex Heuermann's estranged wife Asa Ellerup, center, and daughter Victoria Heuermann, left, departs the Suffolk County Courthouse in Riverhead, New York  on Tuesday, January 16, 2024. Ellerup is the estranged wife of accused serial killer Rex Heuermann, who appeared in court today to face an additional murder charge for the death of Maureen Brainard-Barnes. (Robert Miller for Fox News Digital)

"As District Attorney [Ray] Tierney has previously stated, the work of the Gilgo Beach Homicide Task Force is continuing," a spokesperson said Monday. "We do not comment on investigative steps while ongoing." 

In addition to the Gilgo victims, Melissa Barthelemy, 24; Megan Waterman, 22; Amber Costello, 27; and Maureen Brainard-Barnes, 25, police found seven other bodies scattered over several miles to the west. No charges have been filed in those cases, and there is an active investigation into them.

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Two of the remaining victims, Jessica Taylor and Valerie Mack, were dismembered and dumped in separate locations. Police first discovered their partial remains in Manorville in 2000 and 2003. Additional remains of both victims were uncovered near the Gilgo victims.

In April, police K-9s were seen sniffing through the forest in Manorville, about 40 miles away from Gilgo Beach.

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Police carry evidence outside of a suburban home

Police carrying bags and boxes of evidence from the home of suspected Long Island serial killer Rex Heuermann on Monday, May 20, 2024. Investigators returned to the alleged murderer's Massapequa Park home Monday in a surprise raid – months after they arrested him on multiple murder charges last July. (Kevin C. Downs for Fox News Digital)

"I think it’s directly tied to the search from out east and that box that they found," said Joseph Giacalone, a former NYPD sergeant and cold case expert at John Jay College of Criminal Justice. "I don’t believe in coincidences."

Whatever new evidence led police back to the home is likely more substantial than the chilling scrapbook, he said.

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"They never dug up the basement, and I don’t find it a coincidence that Asa and her kids left yesterday with bags," he said. "As soon as those command vehicles showed up, I knew this was something big. They don’t drag those out just for a looksee."

Portraits of the Gilgo Four victims inset over a wide shot of the marsh behind Gilgo Beach where they were found

The "Gilgo Four" clockwise from top left: Maureen Brainard-Barnes, Melissa Barthelemy, Megan Waterman and Amber Costello. The background shows a wooden cross in the marsh next to Gilgo Beach, New York, where their remains were found in the brush just yards from Ocean Parkway. (Suffolk County Police Department/Mega for Fox News Digital)

Ellerup and her two adult children were out of town on a pre-planned trip when police arrived at the home Monday morning, her attorney said.

She is cooperating with investigators, who have said she is not suspected of playing a role in her husband’s alleged crimes and that she was away on travel during each of the murders.

She filed for divorce shortly after his arrest, but months later said she couldn’t believe the accusations against him.

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"They may have got a tip about another victim where there could be DNA or some evidence that goes to that," said David Gelman, a New Jersey-based defense attorney and former prosecutor. "They could also be seeing if some DNA they found came back and it matches something from the house."

Police outside of a suburban home

Police serve a search warrant at the home of Rex Heuermann in Massapequa Park on Long Island, New York, on Monday, May 20, 2024. Paperwork and tables are being set up to review the evidence that is being brought out of the house. (Kevin C. Downs for Fox News Digital)

Or they may have found DNA in Manorville that they wanted to compare to evidence inside the home, he said.

"It is weird though," Gelman told Fox News Digital. "Obviously the crime scene is contaminated."

Heuermann has pleaded not guilty to murder charges in connection with the Gilgo Four.

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He is being held without bail at the Suffolk County Jail in Riverhead, New York. The county sheriff’s office said it does not comment on specifics about inmate visits but that Heuermann receives visitors regularly.

The case has not yet gone to trial.