A baby-faced son stabbed his father to death inside their Long Island home over the weekend – leaving him begging for help in his last moments, according to cops and neighbors.

Matthew Zoll, 23, allegedly murdered his 61-year-dad postal worker father Joseph Zoll just before 1:30 a.m. Saturday inside the modest high ranch home on Quail Road in Rocky Point, authorities and neighbors said. 

The elder Zoll was rushed to Stony Brook University Hospital, where he succumbed to his injuries, cops said. 

Now, police have launched a manhunt for the still-at-large killer. 

Neighbor Karen Diffley, 64, who had lived at the same address for 28 years – eight of them with the Zolls next door – said she heard the gravely wounded man’s faint cries for help. 

“It was very, it wasn’t a very extremely loud, ‘help.’ You know, it was just kind of, ‘help,’” Diffley said.

“And I was on my phone and I thought maybe it was my phone so I shut it off and I heard it again,” the distraught neighbor went on. “Then I thought maybe it was just my husband’s TV because it was kind of low-key. So I shut everything off and I looked around and I even came out, 1:27, I saw myself on the camera coming out.

“And I looked and I didn’t see anything or I didn’t hear anything after that.”

Joseph Zoll worked as a mail carrier in Riverhead and “had lots of friends,” according to Diffley. He was known in the neighborhood for loving to barbecue.

“I’m in shock. I’m totally in shock. He was a very nice man,” Diffley said. “If I needed help mowing the lawn he would lend us his lawn mower. Very quiet.” 

Local contractor Sean Lamb, 54, described Rocky Point as “a quiet community” where things like this don’t happen.

“This is a tragedy,” Lamb said. “I was talking to him a few times this last week. 

“I couldn’t believe it when someone sent me the picture of Joe and said his son stabbed him. I couldn’t believe it,” he added. “He was very kind.”

Gavan Israel, 23, who lives across the street and studies horticulture at Farmingdale College, described the slain dad as “a super nice guy.”

“We used to talk when we [were] out there washing our cars together on the street,” Israel said. “He would tell me and my brother to come over and take the mulberries when they were in season. Just a nice, quiet, soft-spoken guy.

“Joe had a problem with alcohol years ago but he cleaned up,” Israel recalled. “He was divorced. His wife moved to another town years ago. It was just him and his two sons. His older son, he was OK.

“Matthew, you could see immediately [that] something was off because he was always looking down,” Israel said. “He never really talked. “

Matthew Zoll, who suffers from schizophrenia, briefly went missing in late April, according to an alert from Suffolk County Police at the time. 

“He had a problem a few months ago where he went missing because he went off of his medication,” Israel said. “The local news did a story about it when [police were] looking for him. I’m guessing that’s probably what this started with – a lack of meds.”

Matthew Zoll was still on the loose Monday and cops released his photos in hopes of tracking him down. 

Meanwhile, the family’s downstairs neighbor – who declined to give his name – said he was terrified for his safety as the killer remains on the loose. 

“I don’t like talking about it because it’s upsetting,” the man said. “It makes you feel everything all over again. I’m not feeling too safe here. I asked the cops if … I would be safe here and they said I’d be OK.

“My sister just called and I told her I’m worried. I don’t know, I don’t feel safe,” he added. “But the police told me I’d be OK so that made me feel better.

“I’ve only lived here a month,” the man said. “I don’t know what to do. I’m worried.”

Matthew Zoll is described as a white man with brown hair and brown eyes. He is 6-foot-1 and 150 pounds and has a small scar under his left eye, police said. Police don’t believe the suspect has access to a car.

Anyone with information on Matthew Zoll’s location is asked to call 911, the Homicide Squad at 631-852-6392 or Crime Stoppers at 1-800-220-TIPS.