Double-murder accused Russell John Tully placed stickers on his belongings that place him at the scene of the crime, the Crown says.
The 49-year-old is facing charges over the deaths of Work and Income employees Peggy Noble and Susan Leigh Cleveland by shooting, and the alleged attempted murder of two of their colleagues, in Ashburton in 2014.
He is also charged with setting a man trap and unlawful possession of firearms and ammunition.
The jury was told today that a man matching Mr Tully's description ordered 120 stickers to be made up with three letters on them - a lower case 'i' and 'n' and an upper case 'X' - two weeks before the shooting.
Signmaker Clive Watson said he wanted the 'i' and the 'n' in black and the 'X' in red
Photos were presented in court of items the Crown said belonged to Mr Tully, including a cup, a mountain bike and a shotgun found with him when he was arrested, each with the 'inX' label on them.
The Crown also presented an empty gun cartridge found at the Work and Income office after the shooting, again with the same label attached to it.
The prosecution said the items proved it was Mr Tully who had carried out the shooting.
Accounts from lead-up to shooting
Evidence has previously been given in court that Mr Tully claimed he had returned to Ashburton to die, due to what he said was a skin condition.
A pharmacist who regularly served him, Melissa West, said today the hydrogen peroxide he purchased at least twice a week in the weeks leading up to the shooting was actually something that would cause skin irritation rather than alleviate it.
"It's used for cleaning products, it's used for bleaching fabrics, there's cautions on the label about it being irritating to the skin."
Miss West said she wouldn't normally recommend the product.
An electrician, Peter Sullivan, told the court that on the day of the shooting, he saw a man in a balaclava carrying a shotgun walking quickly towards the Work and Income office and then disappear.
Moments later, while he was on the phone to the police, he saw a group of people run from the office.
He quickly realised something terrible had happened, he said.
"When he got across the road and when the gunman came out, the Maori man shouted out, 'You bloody bastard, you blew her to bits', and that was when I realised things were really serious."
Mr Tully is defending himself but, for reasons that cannot be reported, he was not in court today.
Yesterday, he was ordered to leave court after a loud outburst.
The trial will next week hear evidence from the two women Mr Tully is alleged to have attempted to murder, Work and Income workers Kim Adams and Lindy Curtis.
Today's proceedings were delayed due to legal argument behind closed doors. The reasons for the delay were suppressed.
Earlier this week the trial was delayed for two days, also due to legal argument. The reasons were also suppressed.