Michael Gilbert's headless body was found at a gravel pit pool
The sister of a man whose body was found in a Bedfordshire lake said she had been the victim of violence in the home of those accused of killing him.
The body of Michael Gilbert was found in the Blue Lagoon in Arlesey last May.
Robert and James Watt, of Chertsey Close, Luton, deny murdering Mr Gilbert and other members of the family also deny charges relating to the death.
Patricia Bussey told Luton Crown Court she had been hit with a can during the year she lived at the house.
The court heard Ms Bussey lived at a house in Yeovil Road, Luton, for about a year as the girlfriend of James Watt.
She told jurors: "It started off alright but after a while it got violent. I was hit with a can of hairspray and Michael was there and said it was uncalled for.
"He was told to sit down and shut up and then James smacked him across the face."
She said while she was in the house she witnessed Mr Gilbert being assaulted by various family members.
"He would not talk about it at all. I tried to speak to him, but he would not really answer me," she told the court.
"I did not call the emergency services because I did not want to make it worse for him while he was still in that household."
Andrew Jefferies QC, defending James Watt, suggested she had never been the victim of any violence herself and joined in the violence inflicted on her brother. She said that was untrue.
Robert, 20, and James Watt, 27, deny murder.
The brothers' father Antonio Watt, 70, also of Chertsey Close, is charged with perverting the course of justice.
Their mother, Jennifer Smith-Dennis, 58, is charged with familial homicide and perverting the course of justice.
Richard Watt's girlfriend, Nichola Roberts, 21, of Burfold Close, is charged with murder, familial homicide and perverting the course of justice.
Natasha Oldfield, 29, of Chertsey Close, who is the girlfriend of James Watt, faces the same charges as Ms Roberts.