He has told the court he saw Kemara go into a gun shop in Mt Eden, meet with people and drive others down to the Bay of Plenty.
Under cross-examination from Iti's lawyer, Russell Fairbrother, Mr Horsnell was asked how he knew the text messages were from Iti.
"The information was passed on to me.''
He confirmed that he did not know who was using the cell phone that the police say belonged to Iti.
Earlier, the court heard from Detective Inspector Geoff Jago who was responsible for planting cameras in the Urewera Ranges in 2006 and 2007 as part of a covert police operation.
Mr Fairbrother asked Mr Jago from which direction he approached a whare nui and whare kai in the Ruatoki area.
"I believe, to answer that Mr Fairbrother, at this stage could compromise operational methods and numbers involved,'' Mr Jago said.
He also declined to answer how many police were involved in the operation.
Justice Rodney Hansen said he would not allow the witness to refuse to answer questions. The jury was asked to leave the court room while a legal argument in closed court took place.
The reasons cannot be reported but court reconvened and Mr Jago confirmed he came in from the Waimana area.
Mr Fairbrother also asked Mr Jago if he was aware that the Air Training Corps (ATC) and the Territorials carried out military manoeuvres with guns. He then asked if there was any prospect that the ATC would go to war.
Mr Jago responded: "I wouldn't expect school children to go to war, no.''
Mr Fairbrother also asked Mr Jago if he was aware that one of the police cameras was planted on what is known as the Confiscation Line.
The area has important historical significance to the Tuhoe people because it represents the area of land confiscated by the Crown in the 1860s and 1870s when many Tuhoe people had their crops and homes torched.
Mr Fairbrother handed Mr Jago his copy of Judith Binney's book Encircled Lands which documents the history of the Tuhoe people and contains a map of the Confiscation Line.
"I can't get any correlation between that [the Confiscation Line] and the placement of the camera.''
He went on to say that the police made no "conscious decision'' to put the camera on the Confiscation Line. He said he did not familiarise himself with Tuhoe's history prior to the operation.
Yesterday, the court heard how police found an oven which had been used for target practice and had the remains of exploded molotov cocktails.
Mr Jago told the court that he found broken Steinlager bottles at the site which still contained traces of liquid.
He said the liquid smelt of fuel.
"From memory, one of the bottles had a small amount of cloth which could have been a wick.''
The court also heard how participants in the Urewera camps were taught how to use molotov cocktails, kidnap people and guerrilla warfare.
In his opening address, Crown prosecutor Ross Burns showed excerpts from police surveillance videos taken in the Urewera Ranges, near Ruatoki in 2006 and 2007.
"The purpose was to equip them to kidnap people, commit acts of sabotage and combat - for want of a better word, guerrilla warfare,'' he told the jury.
One of the videos played to the jury shows a group of people getting out of a four-wheel-drive vehicle.
One man can be seen crouching behind the bonnet with a rifle at his shoulder. Several other people rush out of the car and run off screen. "It's really hard to see any lawful purpose for that kind of exercise,'' Mr Burns said.
Other videos show people wearing balaclavas walking through the bush. Some are armed with guns.
The trial continues.
