The Crown says a prisoner was strangled in a revenge attack by another inmate in Auckland Prison.
Petani Fa'avae denies murdering Tue Fa'avae at Paremoremo on 1 March 2009. The two men were not related.
The Crown told the High Court at Auckland Petani Fa'avae provided a stereo cord that was used to strangle the 23-year-old, actively helped to plan the killing and helped cover prison security cameras.
Crown lawyer Wendy Andrews said Tue Fa'avae was strangled in a deliberate and planned revenge attack. She said the dead man was a member of the Bloods gang.
Ms Andrews said two inmates had already been convicted of murder and the focus of this trial was to decide if Petani Fa'avae was guilty too.
She said he didn't strangle the victim but must have restrained him and stopped him fighting for his life.
Mr Fa'avae's lawyer, David Jones QC, said fairness was a critical issue in the trial.
Jurors will go to the prison on Tuesday.