Police investigating the Work and Income murders had possession of alleged shooter Russell John Tully's gun for two days before telling the public they had located it, according to a source close to the probe.
Tully, 48, was detained after a seven-hour manhunt 15km from the Ashburton Winz centre where it's alleged he gunned down three workers.
The sawn-off shotgun police believe he used in the shootings was found "very close" to Tully when he was brought down by police dogs, the source said.
Witnesses have told how the gunman is alleged to have broken down the gun after Monday morning's bloodbath, placed it inside a backpack, and cycled off.
The following day, Detective Inspector Tom Fitzgerald, Canterbury district investigations manager, confirmed that Tully did not have a firearms licence.