Accused Gilgo Beach serial killer Rex Heuermann was nicknamed “Peter” by colleagues — after the bumbling, plodding and sometimes uncouth dad in the popular TV sitcom “Family Guy.”

“We called him ‘Peter,’ the ‘Family Guy,’ mostly because of the way he looked — he was goofy,” a Big Apple architect who worked with Heuermann for almost 20 years told Fox News Digital.

The former colleague, who asked not to be named, said he was shocked by the ghastly allegations against the Massapequa Park married father of two, whom he described as “really friendly and really nice.

“A year ago, my wife was watching a documentary about [the case], telling me how [a] guy was out there killing all these girls on Long Island. I could have never imagined this,” the man said.

“It’s like ‘The Twilight Zone.’ “

Heuermann, 59, was arrested Thursday for allegedly killing three women. He is the prime suspect in the death of a fourth woman, say cops — who have been investigating the deaths of 11 people found in Gilgo Beach near the suspect’s home for more than a decade.

The accused killer is 6 feet 4, weighs about 240 pounds — and bears a striking resemblance to the corpulent character Peter Griffin in the animated “Family Guy.”

Despite Peter’s generally well-intentioned persona, the main protagonist does exhibit a somewhat nasty streak from time to time, including making fun of his daughter Meg and others.

Who were the Gilgo Beach victims?

Suspected serial killer Rex Heuermann — a New York City architect and married dad of two — was arrested in connection with the long-unsolved Gilgo Beach murders. The arrest is tied to the so-called “Gilgo Four,” women found wrapped in burlap within days of each other in late 2010.

The years-long investigation that led to the arrest revolved around the discovery of more than 10 sets of human remains along Ocean Parkway near Gilgo Beach in Suffolk County between December 2010 and April 2011.

Most victims were petite female sex workers with green or hazel eyes. But there were also two exceptions: a 2-year-old girl and a young Asian man.

Melissa Barthelemy, 24

• Barthelemy was a sex worker who lived in the Unionport section of the Bronx and dreamed of one day opening her own beauty salon. She was last seen alive in her basement apartment on Underhill Avenue on July 12, 2009. Heuermann was charged for Barthelemy’s murder in July 2023.

Maureen Brainard-Barnes, 25

• Brainard-Barnes was living in Norwich, Connecticut. She went missing after taking an Amtrak train from New London, Connecticut, to Grand Central Terminal in Manhattan on July 6, 2007. Her remains were found in December 2010. Heuermann was charged for Brainard-Barnes’ murder in January 2024.

Amber Lynn Costello, 27

• Costello, 27, was a sex worker and heroin addict who lived in West Babylon, New York, at a home with a woman and two men. She advertised on Craigslist and Backpage to support her and her roommates’ drug habits. Costello was found on December 13, 2010, after having been last seen leaving her home September 2, 2010. Heuermann was charged for Costello’s murder in July 2023.

Megan Waterman, 22

• Waterman, a 22-year-old mom of one, was last seen on June 6, 2010. She lived in Scarborough, Maine, and earned a living as an escort. She was last seen by her family boarding a New York-bound Concord Trailways bus in Maine. Her body was found on December 13, 2010, on the north side of Ocean Parkway, near Gilgo Beach. Heuermann was charged for Waterman’s murder in July 2023.

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Jessica Taylor, 20

• Remains belonging to Jessica Taylor, a 20-year-old woman working as an escort in New York City, were found in a wooded area in Manorville on July 26, 2003. Her additional remains — initially labeled “Jane Doe No. 5” — were discovered on March 29, 2011, along Ocean Parkway.

Valerie Mack, 24

• Valerie Mack was 24 years old and living in Philadelphia when she went missing. She worked as an escort, using the alias “Melissa Taylor.” Relatives last saw Mack in the spring or summer of 2000 in Port Republic, New Jersey, but she was never reported as missing to the police. Her partial skeletal remains were found in Manorville in September 2000 but were initially known as “Jane Doe No. 6.” More bones were found on April 4, 2011, along Ocean Parkway.

Unidentified Asian man

• The skeletal remains of a yet-to-be-identified Asian man were found along Ocean Parkway on April 4, 2011. It is estimated that the man was between 17 and 23 years old at the time of his death. He was approximately 5 feet 6 inches tall with bad teeth.

‘Peaches’ and her daughter

• An African American woman’s partial remains were discovered in Hempstead Lake State Park back in 1997, and she had become known as “Peaches” because of a bitten tattoo of a peach on her left breast. On April 4, 2011, police uncovered the remains of a toddler, who was about 2 years old at the time of her death. DNA testing confirmed that one of the skeletons was that of the 2-year-old girl’s mother, “Peaches.”

Karen Vergata

• A victim previously referred to as Jane Doe No. 7 has been identified as 34-year-old Manhattan woman Karen Vergata. Vergata is believed to have disappeared around Feb. 14, 1996; two months later, her legs were found in a plastic bag at a park near Fire Island’s Blue Point Beach. At the time of her disappearance, Vergata was believed to have been working as an escort. Two sets of Vergata’s remains were identified in August 2023.

Shannan Gilbert, 23

• Gilbert was a Craigslist escort who lived in Jersey City, traveled with her driver Michael Pak from Manhattan to meet a client, Joseph Brewer, at his home in the Oak Beach Association on the morning of May 1, 2010. She spoke with two neighbors before disappearing. Her body was discovered in a marsh near Oak Beach — about half a mile from where she was last seen alive — on December 13, 2011.

Jessica Taylor, 20

• Taylor, a 20-year-old woman working as an escort in New York City, were found in a wooded area in Manorville on July 26, 2003. Her additional remains — initially labeled “Jane Doe No. 5” — were discovered on March 29, 2011, along Ocean Parkway.

Sandra Costilla

• Costilla was murdered in 1993 but had not been included among the so-called Gilgo Beach victims — until now. Investigators suspected convicted serial killer John Bittrolff in Costilla’s death, but he was never charged in her slaying — which remains one of several unsolved Long Island murders.

Jim Clemente, a former FBI profiler who serves as producer for the CBS show “Criminal Minds,” profiled the person behind the Gilgo Beach crimes in 2011. He described the killer at the time as an educated, intelligent and mild-mannered “sexual sadist” who enjoys watching people suffer, according to Fox News Digital.

“He shows this mask, this cover of kindness, so he can continue to commit his crimes,” the former G-man said. “He’s incredibly good at compartmentalizing, separating his murders from his family life.”

Clemente added that Heuermann was likely “very cruel to certain people” when he thought he could get away with it.

The suspect’s former colleague who also talked to the outlet said he learned about Heuermann’s arrest when a friend in Atlanta sent him a link to a story about the case and asked jokingly if he knew him.

“And I’m like, ‘What the f–k? I do know him,’ ” the man said. “When I saw this whole thing unfold, I was in shock. How was this even possible? It’s crazy. His contact is literally in my phone.”

The architect said he first met the triple murder suspect around 2003 at the firm Mojo Stumer, where Heuermann was a consultant.

“He was always pretty patient with me,” the man recalled. “He taught me how to navigate through the city’s building code.”

The architect said that when he left Mojo Stumer, he hired the hard-working Heuermann as a consultant and expeditor on several residential projects.

“There was nothing weird,” the ex-colleague told Fox News Digital, adding that Heuermann also tried to recruit him around 2009 but he decided not to take the job.

The two remained in touch over the years and grabbed lunch together occasionally, according to the outlet.

Heuermann, who pleaded not guilty to the murder charges against him Friday, was linked to the killings partly because his DNA left on discarded pizza crust was positively matched to DNA left behind on the body of Waterman.

On Sunday night, police began searching a storage unit in Amityville, LI, that was connected to the suspect.

They are looking for possible body parts as well as other “trophies” that the alleged killer may have kept from his victims, police said.

Earlier in the day, state police confiscated a cache of guns from Heuermann’s nearby home in Massapequa Park. Authorities had previously carted off other items from the home, including a large child-like doll, cat food, a scratching post, an empty bookcase and a framed picture.