A row over a supermarket car parking space led to the death of a pensioner, a court has heard.
All three defendants admitted conspiracy to damage property
Three people appeared at Nottingham Crown Court on Monday and denied the manslaughter of Bernard Gilbert, 79.
He collapsed and died after a brick was thrown through the window of his home in Spondon, Derby, on 28 January 2007.
Zoe Forbes, 26, her husband Mark, 40, both of Ripley, and his brother Steven, 22, from South Normanton, admitted conspiracy to damage property.
Michael Auty, prosecuting, alleged the brick attack was not random vandalism but a planned attack linked to a row over a parking space in Asda four days earlier.
Bernard Gilbert died in hospital after the brick attack on his home
Mr Auty said Mr Gilbert had been verbally abusive to Mrs Forbes over the incident, and Mark Forbes became incensed and began plotting a revenge attack.
He traced Mr Gilbert's address through a then-serving police officer, the jury heard.
"A police officer misusing a police computer gives a friend of Mark Forbes most of the address.
"And that friend passes on the information to Mark Forbes," Mr Auty said.
The pensioner is understood to have had advanced heart disease but the prosecution alleges the stress caused by the attack on his window led to his death.
Mr Gilbert's behaviour during the argument in the car park had been "abusive" and "over the top" but the Forbes began to devise their own plan instead of calling the police, the court heard.
In one text message, Mark Forbes told his wife: "I have got someone onto it so fingers crossed.
"I will get an address then we can smash his car to bits, then his hire car, then whatever he gets after that until he dies."
In another message, he said: "I have got his address and his windows are getting blown out tomorrow night. If he was younger I would kill him."
Forbes subsequently told police he had only been "bigging himself up".
Mrs Forbe did "absolutely nothing" to dissuade her husband and everything to encourage him as he planned his attack, the prosecution said.
The case continues.