Gardaí who saw the body of a man, whose nephew is on trial in the Central Criminal Court for his murder, described the scene as "horrific".
Garda Thomas O'Connor told prosecuting counsel Mr Patrick Gageby SC that he still had trouble believing "how gruesome it was".
"I have never seen anything as bad as that in life or in movies."
Henry McLaren (aged 34) of Edenmore Drive, Raheny denies murdering 61-year-old Thomas Demspey at Edenmore Drive on February 10, 2007.
Gda O'Connor told Mr Gageby that Mr Dempsey was lying face down in the hallway of his home when gardaí forced entry. He had severe head injuries.
Gda O'Connor said it was immediately obvious that Mr Dempsey was dead. There was a portion of his skull missing and Gda O'Connor said he could not tell what colour clothing he was wearing as it was all soaked with blood.
There was a large amount of blood pooled on the floor and the walls were spattered with blood and pieces of bone.
In his opening speech to the jury, Mr Gageby told them that the main issue they had to look at was the accused's mental health at the time of the incident.
Ms Elaine Dillon, a neighbour, said she heard noises coming from Mr Dempsey's house. She said she knew Mr Dempsey by name and was aware that his nephew, the accused, stayed with him on and off.
She said she was coming back from a friend's house when she heard screaming.
"First it was like a bird squawking then I looked around and I thought it was kids," she said.
When she had located the noises she called on a neighbour to ask them to call gardaí. The noises where continuing.
"I could hear screaming first then I could hear noises that sounded like a whipping noise."
More and more neighbours came out onto the street as the noises continued. After a while they stopped and the door opened.
Ms Dillon said she was standing outside her house, directly opposite Mr Dempsey's house and saw Mr McLaren come to the door.
"I could just see two feet and the hall door was open."
She asked Mr McLaren where his uncle was. "He just said: "He's in Hell. He's in f***ing Hell. He's burning in Hell."
He was extremely agitated and went back inside. Through the half open curtains of the living room she could see him walking around the room.
Gda O'Connor told Mr Gageby that he arrived on the scene after Mr McLaren refused to allow ambulance and fire crews into the house.
Mr McLaren was shouting incoherently as he approached the house. He could see from some distance away that he was covered in blood.
"There was a lot of blood spattered across his face. It looked as if something that exploded in his face."
Gda O'Connor said that as he got closer he could hear what Mr McLaren was shouting.
He was screaming: "Black people, I need black people around me."
He said that he "needed a black woman".
When Gda O'Connor asked him was there anyone injured inside the house he said that "Jimmy Hendrix" was injured.
Gda O'Connor told Mr Erwin Mil Arden SC, defending, that Mr McLaren seemed to be looking straight through him and looked "very odd".
Gardaí forced entry into the house and Mr McLaren ran upstairs and barricaded himself into one of the bedrooms.
Mr McLaren was eventually arrested by armed gardaí and taken into custody.
Dr Amir Kahlil told Mr Gageby that he was called to Coolock garda station to treat the accused. Mr McLaren told him he suffered from a psychiatric illness and admitted that he had not been taking his medication.
The trial continues tomorrow before Mr Justice Barry White and the jury of seven men and five women.
It is expected to finish within the week.