Troubled Sydney home site of man's death

The Sydney home of a man who died after a family brawl had been wracked by drugs, mental illness and sickness, a family friend says.

Police were called to break up a fight between brothers at a northern beaches home in Warriewood on Monday evening.

Yelling could be heard from the side of the house where three brothers were arguing.

Police say a 45-year-old man was unresponsive and taken to Mona Vale Hospital in a critical condition but died on arrival.

"(He) was a very loving person ... but drugs ruined him," a family friend said of the 45-year-old, who suffered from mental illness.

"Ice is bad."

The friend, who did not wish to be named, said the man had emphysema and could have suffered a heart attack during the brawl.

"He had already written his will out, that's how sick he was," she said.

The cause of death of the 45-year-old man is still unclear, police said on Tuesday.

Two male relatives aged 40 and 43 were arrested at the home on Monday night but have since been released, police said.

Neighbours say the home has been troubled for years.

"It's not the first time there's trouble," one neighbour, who did not wish to be named, told AAP.

Another neighbour said the home was noisy and one of the men, who suffers from a mental illness, could be heard yelling out to the street at times.

"He rails at the universe from his balcony," the neighbour said, adding it had been this way for years.

"We aren't surprised something like this has happened here, but it's very sad."

The messy home has broken furniture piled on the front yard, blankets covering the windows and a tattered teddy bear poking through the fence.

Police have left the scene and investigations are continuing.