'If they had just listened to Yonkers sooner': How two cops helped solve Son of Sam murders

David Propper
Rockland/Westchester Journal News

Joyce Intervallo was terrified that the Son of Sam would shoot her husband dead.

In the summer of 1977, David Berkowitz, infamously known as the Son of Sam, was terrorizing New York City, randomly shooting victims at night with a .44 caliber revolver. He shot 15 people, killing six and wounding seven in 1976 and 1977. It resulted in the largest manhunt in the city's history.

About 10 miles away, Yonkers police officer Peter Intervallo Sr. and his partner Thomas Chamberlain were so sure Berkowitz was the serial killer that one summer day Intervallo climbed up the fire escape of Berkowitz's building to look inside his seventh-floor apartment. 

Yonkers detectives Peter Intervallo and his partner Thomas Chamberlain after the arrest of David Berkowitz in 1977.

Intervallo told his wife of his plan beforehand, a plan that made her nervous. He assured her he'd be OK. 

"I was scared to death because if (Berkowitz) gets spooked he could shoot you right from inside," she said last month from her home in Mahopac, shortly after her husband had died at age 69.

On one of the hottest days of the year, the windows were covered in tarp. That's when Intervallo and Chamberlain knew New York City's most sought-after murderer was discreetly living on Pine Street in Yonkers. 

Intervallo started telling other officers, friends and acquaintances that when Son of Sam wasfinally arrested, his initials would be D.B. He told his wife about Berkowitz when it was still just a well-educated guess, before the rest of the world would come to know the deadliest serial killer in New York City's history. 

"They were quite firm, they really thought they had something really important and serious here," Joyce said. "That's why he went around saying the initials, he wanted people to know he was sure that he knew."

Yonkers detectives Peter Intervallo and his wife Joyce after the arrest of David Berkowitz in 1977.

Intervallo died on May 8, leaving behind Joyce, one daughter and two sons, who both now work for the Yonkers Police Department. Only his daughter, Amorette, was alive and only just a toddler, when Intervallo was looking into Berkowitz. 

He retired from the force in 2010 after 37 years on the job, most of it as a detective. Highly respected for his meticulous investigative work and known as a family man away from the job, the Son of Sam case was the pinnacle of Intervallo's career, earning him commendations and a promotion.

While Intervallo rarely talked about the case, Joyce wants her husband's heroics to be remembered, even if they might always be overshadowed by the NYPD's collar of Berkowitz on Aug. 10, 1977. The contributions of Intervallo and Chamberlain were highlighted shortly after Berkowitz was apprehended, but as the years passed their work has largely been ignored in books, documentaries and movies about the famous case.

"That New York City got all the glory for all of this when the reality was, if they had just listened to Yonkers sooner they probably could have prevented some of it," said Yonkers Det. Keith Olson, president of that city's PBA.

Shortly after her husband's death, Joyce Intervallo invited reporters into the couple's Mahopac home. Based on past conversations with him, dozens of news clippings and old evidence that's been photocopied, she detailed step-by-step how Intervallo and Chamberlain helped crack the case of the so-called ".44 Caliber Killer."

Even when others doubted him, Intervallo stood his ground: D.B. was the Son of Sam. 

Dog shootings were the first clue

Intervallo's link to Berkowitz, now serving a life sentence in Shawangunk Correctional Facility in Ulster Countywas born from happenstance. The killer's 35 Pine St. apartment was in the young cop's southwest Yonkers patrol area. He was only 25 at the time. 

More Son of Sam: Berkowitz arrested in Yonkers 43 years ago

Sniper mystery: Was Son of Sam behind Westchester 'Dartman' attacks?

Dog shootings and mysterious letters initially put Berkowitz on Intervallo's radar.

On Christmas Eve 1976, Intervallo and Chamberlain were called to probe the shooting of a German Shepherd. By that point, Berkowitz had already shot six people in three separate incidents in the Bronx and Queens, killing one, Donna Lauria. She was 18. 

A copy of a letter that David Berkowitz wrote to Sam Carr in 1977. This is from evidence obtained by Yonkers police.

Four months later, the Yonkers cops investigated the shooting of a black Labrador retriever hit by a .22 caliber bullet in the dog's backyard. The Labrador was owned by Sam Carr, the apparent "Sam" in Son of Sam. Both dog shootings occurred close to Berkowitz's home. 

After searching the area, Intervallo and Chamberlain determined the only window that had a direct line to Carr's Warburton Avenue backyard was Berkowitz's apartment 7E.

Around the same time, Carr received two anonymous letters from Berkowitz, one that read in part: "I have asked you to kindly stop that dog from howling all day long, yet he continues to do so. I pleaded kindly with you. I told you how this is destroying my family. We have no peace, no rest."

But an anonymous get-well card sent to Berkowitz's former landlords, the Cassaras, tied him to the dog shootings. Before moving to Yonkers in April 1976, Berkowitz lived in New Rochelle and rented from the Cassaras. 

The card's return address listed Sam Carr's home, even though the Cassaras and Carr did not know each other. Even odder, no one in the Cassara household had fallen ill or injured. 

When Nann Cassara contacted Carr to inquire about the get-well card, the conversation shifted to Berkowitz. Cassara told Carr that Berkowitz hated dogs and had recently moved near Carr's house in Yonkers. 

When that information was relayed to Intervallo and Chamberlain, they knew they had their dog shooter.

How they pieced together the clues

Soon after, Berkowitz went from local dog shooter to Son of Sam suspect in the eyes of Intervallo and Chamberlain

In letters sent from Berkowitz to the late newspaper columnist Jimmy Breslin, he made reference to the Wicked King Wicker and John Wheaties – Rapist and Suffocator of Young Girls. Both names raised the suspicion of Intervallo and Chamberlain because there was a Wicker Street a stone's throw from Berkowitz's home and Carr's son's nickname was Wheaties; his daughter's first name was Wheat. 

Joyce Intervallo talks about her late husband Yonkers detective Peter Intervallo's involvement in the arrest of David Berkowitz in the Son of Sam case while in her Mahopac home May 20, 2021.

His letters also mentioned Sam, which Intervallo and Chamberlain thought could be a reference to Sam Carr. By the time the letter was penned to Breslin on May 30, 1977, Berkowitz had killed five people and terror was only rising in the Big Apple. 

At that point, Intervallo and Chamberlain believed Berkowitz was worth looking into and told NYPD detectives who happened to be in Yonkers on Aug. 5. 1977. It was the first time Berkowitz's name was mentioned to the NYPD, Joyce believes.

"We think we may have information on who Son of Sam might be, but if you think we're crazy just tell us and we'll get out of here," Joyce recalled Intervallo telling detectives.

The next day, a fire was set at the door of Craig Glassman, who lived in 6E directly below Berkowitz, and letters were also sent to him with handwriting similar to the notes sent to Carr and the Cassaras, Intervallo noticed. 

Convinced as ever, Intervallo and Chamberlain again contacted the NYPD, but were ignored with the department receiving more than 100 tips daily. Joyce said many officers were skeptical of them.  

"It was incredibly intelligent and required extreme attention to detail for him and his partner Tommy to really piece such bizarre events together like that," said Intervallo's youngest son Anthony, who is a Yonkers police detective.

Satan behind the killings

David Berkowitz lived in Yonkers, worked as a postal worker in the Bronx and shot 15 people across three New York City boroughs — the Bronx, Queens and Brooklyn — over the span of roughly a year.

Young women were dying their hair lighter colors because it was believed the Son of Sam targeted brunettes. Lovers' Lanes, where Berkowitz would find his victims, all but disappeared. The fear was palpable as night fell in the city that's supposed to never sleep.

David Berkowitz after his arrest in 1977. This photo is from evidence obtained by Yonkers police.

Berkowitz was 24 when he was arrested and, after pleading guilty, was ordered to serve six consecutive life sentences. There is little chance he will be paroled.

Before he began his shooting spree, Berkowitz served in the U.S. Army and was honorably discharged. Leading up to his job with Post Office, he held several jobs, including taxi driver, security guard and construction worker.

In a 1997 letter to Gannett, the parent company of The Journal News, Berkowitz wrote he was very sorry for his actions and took full responsibility for them.

He claimed Satan completely took over his body back then.

“My mind and soul had become poisoned,” Berkowitz wrote. “Today I have nothing but regret for the things I have done and the lives that were lost.”

A born-again Christian, Berkowitz, who was raised by adoptive Jewish parents, wrote that Jesus Christ has forgiven him for the murders.

“I continually pray for the families of those whom I hurt will heal from their wounds,” Berkowitz wrote in 1997. “Right now I have to go forward with my life. The tragic past is fast becoming a distant memory.”

Joyce said her husband had compassion for Berkowitz, though he firmly believed he should never be released from prison.

“He just felt he was a very sick individual,” Joyce said, adding that her husband "kind of felt sorry for him."

'Not a crier at all'

A parking ticket and an Aug. 9 phone call to Yonkers cracked the case.

After Berkowitz struck again on July 31, 1977, the NYPD checked parking summonses in the area where Stacy Moskowitz and Robert Violante were shot in Violante's car in the Bensonhurst section of Brooklyn. Moskowitz, who was a 20-year-old secretary, was killed while Violante survived. 

One of the tickets issued nearby the slaying was Berkowitz's 1963 Ford Galaxie. 

An NYPD detective, James Justus, called Yonkers police. The dispatcher on duty happened to be Wheat Carr, daughter of Sam Carr. After Justus inquired about Berkowitz as a witness, she told the detective that Intervallo and Chamberlain thought he might be the killer.  

The apartment of David Berkowitz after his arrest in 1977. This photo is from evidence obtained by Yonkers police.

When Chamblerain told Justus about the evidence they had, he dropped the phone. A day later, Berkowitz was arrested in Yonkers by the NYPD. 

"New York City knew, they knew where they got their information from," Joyce said, referencing how Intervallo and Chamberlain were among the police officers honored by New York City. 

Intervallo wasn't there for the arrest, but knew it was coming. He learned about his capture when a breaking news banner came across his television while watching the Tonight Show with Johnny Carson.

He started to cry. 

"He was not a crier at all, I think it was just the relief that this guy who killed so many young people was caught and all the work that they put in and all the long hours and that they were right," Joyce said. "That they were on the right track."

Multiple-shooter theory dismissed 

Intervallo's death came three days after a new docuseries premiered on Netflix about the Son of Sam shootings. The six-episode series, called "The Sons of Sam: A Descent into Darkness," explored whether Berkowitz acted alone or if the killing spree was the work of a Satanic cult. 

The series centers around the investigative work done by the late journalist Maury Terry, who reported on the story for decades and firmly believed Berkowitz was part of larger group that committed the shootings, including Sam Carr's son John and Michael. Terry wrote for Gannett newspapers.  

Intervallo and Chamberlain both rejected that theory, and thought Berkowitz acted alone.

“Because guess what, Berkowitz got arrested and all the killings stopped,” Joyce said of Intervallo's reasoning. “He felt he was a loner and living in his own head.”

The series producers never reached out to Intervallo for an interview, Joyce said, and her husband never watched it. 

Beverly Chamberlain noted that when Terry called her husband after the release of his book, "The Ultimate Evil" that presented the cult theory, Chamberlain hung up on him.

'He's a legend' 

Following the Berkowitz's arrest, credit was largely given to the NYPD for catching the killer. That's when Joyce called a news station to alert them of her husband's and his partner's work. Their son explained.

“My father was very humble and he wouldn’t want recognition for the work that he did, he would always just say he was doing his job,” Anthony, one of Intervallo's sons, said of his father's career. “But my mother’s always been the driving force to want him to be recognized for everything that he did.”

Though typically unassuming, the two Yonkers cops were proud of the recognition and promotion they got as a result of the Son of Sam case, Anthony noted. 

Yonkers detectives Peter Intervallo holding his daughter with Yonkers mayor Angelo Martinelli after the arrest of David Berkowitz in 1977.

Once their effort was highlighted, Intervallo and Chamberlain were honored by former Yonkers Mayor Angelo Martinelli and promoted to detective by the City Council. And former New York City Mayor Abe Beame also honored them, part of a larger ceremony that celebrated dozens of New York City police officers. 

Family and friends believe the two men never received the credit they deserved, especially over time as the case has been dissected. 

Beverly Chamberlain said her husband got tired of talking to reporters over the years because after answering countless questions, his and Intervallo's part in the case was only sparsely noted, if it was at all. She even questioned why Yonkers police back then were not applauding their own officers more. The department quickly told the two patrolmen not to say anything about the case, Beverly recalled. 

Today, Intervallo and Chamberlain, who was on the job for 33 years, are both revered in the department. Anthony said his last name is instantly recognized. 

"The guys I work with, they know," Anthony said of his dad. "He's a legend." 

'How much it meant to him'

Intervallo's law enforcement legacy is carried on my his two sons, Anthony and Peter Intervallo Jr. When Anthony made detective, he took his father's badge number, 692. They are the only two officers to ever use it.

Peter Jr., who works in the department's technical assistance response unit, wears the same silver shield, 716, as his father. The wisdom he passed down to both sons has been invaluable, Joyce said.

"He was a very accomplished police officer and detective so we would hear stories and stuff like and of course I wanted to follow in my father's footsteps," Peter Jr. said. 

One of those stories was of course the Son of Sam case. 

From left to right: Sons and current Yonkers police officers Peter Intervallo Jr. and  Anthony Intervallo and father and former Yonkers detective Peter Intervallo Sr.

While Intervallo would turn down media interviews, he did invite his children's classmates over if they wanted to do a book report on the Son of Sam. The subject was also occasionally dining room table talk as recent as this year.

“He started going back through the entire story and started tearing up and that was probably the best I’ve heard ever it explained from him, and you could see how much it meant to him,” Anthony said of the last time his dad discussed the case. 

'Tom and Pete were right'

Before Intervallo's death last month, he mourned the loss of his partner and friend Thomas Chamberlain, of Irvington, five years earlier. The work on the Son of Sam case forged a close relationship between the two, Beverly said. 

Intervallo was the first person to call Beverly when Chamberlain died in January 2017. She recalled how broken up Intervallo was over it and was later told by Joyce he was sobbing when he heard his former partner died. 

"There was just something special between the two of them, what they went through with the Son of Sam," Beverly said. "They went through the hell, I'll tell you that."

Joyce said the two were like brothers. 

When no one else believed them about Berkowitz, they had to rely on each other. 

"Everybody had a Son of Sam, it wasn't just Tommy and Pete, a lot of people thought they knew who the Son of Sam was," Beverly said. "But it turned out Tom and Pete were right."

David Propper covers Westchester County. Reach him at dpropper@lohud.com and follow him on Twitter: dg_props. Our local coverage is only possible with support from our readers.