The people over the fence from Dustin La Mont were involved in drugs and gangs with the jury shown evidence of meth bags and Mongrel Mob patches.
La Mont, 26, is on trial for murdering Nathan Pukeroa, 24, and wounding Devaray-Junior Heremia Cole-Kuruaji, 22, with intent to cause grievous bodily harm by stabbing them both in the neck during an altercation over a loud party in Auckland.
The alleged attacks took place on Renton Rd, Mt Albert on December 2, with the Crown alleging La Mont's feelings towards his neighbours rising from annoyance to "a state of anger and frustration" in the 21 months before.
However, the defence says La Mont acted in self defence to two large men threatening him.
Today at the Auckland High Court, Detective Martin Friend gave evidence about what was found at the house next to La Mont's flat.
Amongst red bandannas, tattoo materials, numerous sim cards and a Mongrel Mob patch to be sewn on a jacket, seven drug bags were catalogued, which either contained what was most likely meth, or traces of the drug.
Point bags and a ziplock bag capable of holding an ounce of meth and a glass pipe were also found - though the items were never analysed so Friend could not say definitively that any of the items were used for meth.
But he accepted it was "likely" due to his experience as a police officer, when questioned under cross-examination by La Mont's lawyer, David Hoskin.
Yesterday the jury heard how La Mont staged surveillance on his neighbours, documenting movements, vehicles and taking photos and videos as evidence in his plan to get them evicted.
He also shared his frustrations on social media, tweeting: "Rarely have I been more provoked to go on a murderous rampage."
And on the night of December 2, La Mont tweeted: "Sounds like the mongrel shitf***s next door are having another party. Yipee."
Pukeroa and Cole-Kuruaji spotted him and there was a confrontation outside with prosecution lawyer Steven Hazard telling the court La Mont thrust the knife deep into Pukeroa's neck, severing his carotid artery causing him to die within minutes.
It is alleged he then stabbed Cole-Kuruaji in the right of his neck, narrowly missing his carotid artery and jugular and, with immediate hospitalisation, he survived.
Hazard said La Mont then ran around the block, back to his flat and "took immediate action to cover up what he'd done" by bleaching his beard, cleaning and disassembling the knife, then shaving his beard.
He told his girlfriend he was self-harming in the back shed at the time of the attacks.
La Mont then ditched the items on his walk to work but ended up painting himself into a corner with his false alibi and police finding blood on his shoes, the only item he didn't ditch.
The trial continues.