Pictured: Long Island son Joe DeLucia Jr who killed family then himself in shock murder-suicide after his mother's funeral

The distraught son who killed four relatives in a horrifying murder-suicide 'didn't want to move out' after his mother's death - so he shot dead his entire family.

Joe DeLucia Jr, 59, opened fire with a shotgun inside the family home on Wyoming Court in Syosset, on Long Island, just before noon on Sunday.

Neighbors heard anguished wailing, crying, and screaming before DeLucia fatally shot himself in the chest on the front lawn minutes after the massacre.

His mother, family matriarch Theresa Martha DeLucia, 95, died on August 19 and was buried on Friday, which he was still greatly distraught about.

Distraught son Joe DeLucia Jr (left) killed four of his family before turning the gun on himself as they met to discuss winding up his late mother's affairs

His mother, family matriarch Theresa Martha DeLucia, 95, died on August 19 and was buried on Friday, which he was still greatly distraught about 

DeLucia, who has mental health issues, is believed to have been unable to handle the prospect of moving out of the family home, where he lived all his life.

He grabbed his mother's favorite old white-painted metal chair she always sat in on the patio and dragged it to the lawn, where he sat down and shot himself.

The chair still sat where he left it on Monday morning.

Neighbor Randi Marquis said her door camera filmed DeLucia coming out of the house and shooting himself.

'I saw everything. He just cried out loud - it was an ugly sound - it sounded like a bird being eaten alive,' she said.

'He knew what he did. He had the gun, he shot himself in the heart and then fell forward.'

Real estate agent Mary Macaluso was asked to come to the house on Sunday to discuss selling the property, but arrived to find a crime scene.

Marquis told DailyMail.com that Theresa's will declared the house should be sold and anyone living there had to move out.

'He was afraid that he was going to be homeless... His sister told me that he stopped taking his medicine on Saturday, and once he stops taking the medicine, that's it,' she said.

'He had this planned. I don't know where he got the gun from.'

Police said psychiatric medicine was found in the home during a search, along with a 12-gauge pump-action shotgun that was legally bought by DeLucia.

Detective Captain Stephen Fitzpatrick said neighbors claimed DeLucia told them: 'If you hear gunshots, don't bother calling 911, it'll be too late'.

DeLucia opened fire inside the family home on Wyoming Court in Syosset, on Long Island, just before noon on Sunday

The victims were DeLucia's brother Frank DeLucia, 64, who flew in from North Carolina, sister Joanne Kearns, 69, from Tampa, and another sister, Tina Hammond, 64, from Long Island, along with her 30-year-old daughter Victoria.

All four were found shot to death in the den at the back of the house when police went in after finding DeLucia's body outside.

One of the sisters was said to have offered to DeLucia in at her home and look after him, and it is not clear why he turned her down.

Marquis explained that the gathering was supposed to double as a birthday party for one of DeLucia's sisters.

She was at home organizing food for the party, intending to come after Macaluso was finished discussing the house sale, when she realized something was wrong.

'When I saw the ambulance I just knew,' she said, though she initially only thought DeLucia only took his own life.

'When I went over to the neighbor and a neighbor said, "he took all of them"... It was selfish.

DeLucia's sister Tina Hammond, 64, still lived on Long Island and helped look after her mother and brother

Oldest sister Joanne Kearns, 69, from Tampa, was in town for the funeral

'I didn’t see this coming. God forbid I was going to be there. I was going to go there and sing happy birthday and I told them not to eat I was going to bring a lot of food.'

Marquis said DeLucia was born with the umbilical cord wrapped around his neck and was deprived of oxygen during birth.

She said he was a retired paramedic who worked as a mechanic in Hicksville and drove himself to work, then home right away to look after his mother. 

'He loved his mom. He was always there. He was there every day in the hospital,' she said.

Marquis said DeLucia's sister, Hammond, with whom she was close friends, told her she was worried about her brother in the days after their mother's death. 

She said she visited Hammond on Saturday night and gave her birthday presents, along with her daughter Victoria who turned 30 last month.

'Randi, he is not taking his medicines,' she said Hammond told her.

Hammond told her she was concerned her brother may take his own life but thought he was 'all talk', but Victoria said, 'no he is going to do it'.

'I was there on Friday and I was looking at pictures in the house and I asked Joe how he was. He looked at me with this eye like don’t talk to me,' Marquis said.

Victoria Hammond, 30, was Tina Hammond's daughter and DeLucia's niece

Victoria, pictured with her boyfriend, was killed along with her mother, aunt, and uncle

She said on Friday the house was packed and DeLucia could carried out his mass murder then, but said 'he waited'.

'He knew what he was doing,' she said, as he was aware of the meeting with the real estate agent.

'I miss her Tina and her daughter Victoria. I am angry he took his whole family.

'You have issues and you may be homeless, but don’t take anyone else's life or your own.’

Marquis said she tried to explain to DeLucia many times after his mother died not to harm himself, and that he could live with Hammond.

'He was sitting in the front yard and said, "I'm going to be homeless". It's very unfortunate and I can't imagine,' she said. 

Marquis said on Wednesday she went to his auto body shop, and tried to reason with him.

‘I told him your mom would never approve of this she did not teach you this and he said you don’t understand,' she said.

'I told him in the Catholic religion you don’t do that... now is not your time. All your sisters and brothers are here.'

DeLucia' grabbed his mother's favorite old white-painted metal chair she always sat in on the patio and dragged it to the lawn, where he sat down and shot himself

DeLucia grabbed the chair from here on the house's patio, next to another rusted chair and table where his mother often sat

Samuel Landsman, a psychologist, who lived across the street for the past 30 years recalled one incident when he saw DeLucia completely unhinged.

'While working on his car he got really really upset. I guess he made some type of mistake and started screaming,' he told DailyMail.com.

'I was certainly surprised he killed other people. I wasn't expecting anything like this to happen - that he would kill his family.'

Marquis said Theresa had a bad fall in April and her daughter said her health began to decline after she stopped going to physical therapy.

'I was close with Terry, I took care of her sometimes, visited her, cooked for her, her children used to play in my backyard,' she said through tears.

'I was also very close with one of the daughters and I met all of her siblings again [at the funeral] on Friday.'

Marquis said the 30-year-old woman was Theresa's oldest grandchild, who had just finished university and was figuring her life out.

'She was also like a daughter to me, since I have four boys but never a daughter,' she said.

DeLucia posted this number plate as matching his state of mind, though it was not clear if it was his car or just one he saw

Officers found DeLucia with a self-inflicted gunshot wound on the front lawn of this Syosset, New York home on Sunday - and four other victims inside

DeLucia's social media posts painted a picture of a deeply unhappy man who was frustrated with the world and his place in it.

On August 18, the day before his mother died, he changed his Facebook cover photo to an image of a car number plate reading 'DEPRSSED'.

Other posts complained about friends trying to get mechanical work, the struggles of the New York Jets NFL team, and the standard of paramedic training.

'If you do not like my price and feel that I am too expensive then go to another shop. I am not running a charity,' a post from last September read.

'I have bills to pay. tools and equipment cost money. Even if I am looking at your vehicle that takes time.'

Another post declared Bad Day by Daniel Powter to be 'my theme song for work'. 

DeLucia used this 12-gauge pump-action shotgun that he legally bought, to gun down his family

The inside of DeLucia's car, still parked at the house

Police said they responded to a call at 11.58am about shots fired in the quiet cul-de-sac where they found a man suffering from a self-inflicted gunshot wound on the front lawn.

Fitzpatrick said police spent 10 hours combing through the property trying to make sense of the massacre.

'The perception of Joseph Jr was he was being cut out of the will and was going to be displaced without a place to go,' he said 

He said his siblings tried to assure him this was not the case, and he would be moved out of the house and looked after, but he didn't believe them. 

'Because of that perception, he decided that day to get a loaded, Mossberg shotgun, 12 gauge, approached them in the rear area of the house, and from the kitchen, fired 12 shots, striking all four of them multiple times,' he said.

Fitzpatrick said there was a welfare check on the home in 2022 but DeLucia 'was not displaying any signs of anything that we would take action'.

'He had past mental issues, psych issues, that were reported to us,' he said. 

Police said they responded to a call about shots fired in the quiet cul-de-sac

Police said DeLucia took a loaded shotgun and approached them in the rear area of the house, and from the kitchen, and fired 12 shots, striking all four of them multiple times

"He was kind of a hoarder, spent all his money on his tools and stuff. The house was pretty much packed with tools and stuff involved in auto mechanics.

'He lived there all his life, never lived on his own. So you can see the mindset where his world was now changing, at 59 years old, and he was panicking.'

Nassau County Police Commissioner Patrick Ryder said it was 'probably one of the most horrific scenes I have seen in 41 years'.

'Walking into the backroom of that house with these four victims lying after being shot multiple times and also the shooter being on the front lawn committed suicide,' he said.

Ryder chastised those in the community who knew DeLucia was distressed, but didn't say anything.

'There was talk in that community about the distress of this shooter that he decided he did not want to leave his residence after his mother died,' he said.

'We are asking our communities not to sit back, be our eyes and ears and let us know what is going on.'

Nassau County Police investigators probe scene, spending 10 hours looking for clues

The mailbox with the family name outside the house

Ryder red flag laws that allowed police to seize weapons if someone was considered a threat to themselves or others 'exist for a reason'.

Fitzpatrick added: 'We're not saying this incident could have been averted, but maybe it could. But if he was reported to be mentally unstable, this may be illegal to possess.'

Landsman said he was working in his office when his ring camera recorded when DeLucia shot himself.

‘I was really shocked. I never expected this to happen but when I saw the police and ambulances the first I thought, "Oh my god I wonder if Joe killed himself",' he said.

Macaluso said she was supposed to be meeting relatives at the home at around noon - but by the time she arrived, authorities had already closed the street. 

'The kids were all here for the funeral, and they asked me to come look at the house,' she said.

The house is is estimated to be worth nearly $900,000 by Zillow, and Theresa wanted it sold

Cars in the driveway of the home that will never be retrieved by their owners

She explained that one of Theresa's children asked her to meet with the family so they would know what to do before listing the home, which is estimated to be worth nearly $900,000 by Zillow. 

The family wanted the assessment done quickly because two of the family members came from out of town for the funeral, and were headed back soon.

DeLucia lived in the house his entire life, and neighbors said losing the home was just too unbearable for him.

Other neighbors noted that they heard gunfire, as they remained shaken up by the grisly scene.

'At first I heard it was a murder-suicide, and that's pretty bad,' Mike Steffens told ABC 7. 

'And then I heard four people murdered and then a suicide, so it was something you don't hear very often, let alone in your own town.'

Another resident, Wendy Paisner, called the murder-suicide a 'tragedy for the family' in her remarks to NBC 4 New York. 

DeLucia lived in the house his entire life, and neighbors said losing the home was just too unbearable for him