Russell John Tully claimed he wasn't fit to stand trial, but was sentenced to a minimum of 27 years.

The Ministry of Social Development did not assess the risk to staff from shooter Russell Tully, despite staff concerns about his behaviour before the day of the murders.

Former police officer, now investigator with Corporate Risks Ltd, Russell Joseph looked at the fatal shooting in the Ashburton Work and Income office and reviewed other reports.

"There was no process in place despite concerns of staff. MSD did not put anything in place to assess the risk to staff from Tully," he told a Judge Jan-Marie Doogue in Wellington District Court on Wednesday.

DAVID WHITE/FAIRFAX NZ Safety expert Roger Kahler believes bulletproof glass in Work and Income offices might deter a gunman.

Joseph said Tully carrying a gun was irrelevant as the office did not cater to any level of security threat.

READ MORE:

* Guards, locked door may have saved victims

* MSD pleads guilty

* Killer Russell Tully lodges appeal

* Tully unmoved by 27-year jail term

"It had no level of security in place."

DEAN KOZANIC/FAIRFAX NZ The sentencing of Russell John Tully in the Christchurch High Court.

The Ministry of Social Development pleaded guilty to a charge of failing to keep their staff safe, but is disputing that the open-plan design of their offices should have been altered.

Tully was found guilty of the murders of Susan Leigh Cleveland and Peggy Turuhira Noble and attempted murder of Kim Elizabeth Adams, receiving life imprisonment with a minimum of 27 years. He is appealing his convictions and sentence.

Tully entered the Ashburton office at 9.51am on September 1, 2014, and fired at Noble, who was on the reception desk, killing her almost instantly.

He then fired at Adams as she fled to a back room. She told the jury of feeling a "swish go past my face really close".

He found Lindy Curtis hiding under a desk with a client, and fired at her. As he fired, she lifted her leg and was hit in the thigh.

Tully then moved to the back of the building where he saw another of his specific targets, Cleveland. She was the staff member he was most dissatisfied with. He shot her three times, killing her.

Joseph said a controlled entry, with or without bulletproof glass, would have given time for the alarm to be raised and staff to get to safety.

He criticised a security report from 2012 he said was flawed because MSD had already indicated they would not look at changing their open-plan office design.

MSD had a trusting relationship with clients and wanted a layout that encouraged workflow and that clients could access the service to help them to become independent.

Joseph said he strongly disagreed with that philosophy.

"It places the needs of the client ahead of the security of their staff. A properly-designed workplace does not inhibit workflow or inhibit collaboration, instead it fosters interaction with staff."

He said he noted that since the shooting MSD have moved to controlled entry now and as far as he was aware it had not impacted on their ability to do their job.

Work and Income offices needed bulletproof glass between their clients and staff, an international safety expert told the court.

Roger Kahler from Australian company InterSafe, which looks at risks and reports on accidents, has been explaining a report he wrote about how the open plan layout played a part in Tully's shooting spree.

Lawyer for the ministry Brent Stanaway read out part of a statement from chief executive Brendan Boyle that said the ministry considered the open-plan office was an effective design to manage the risks of violent clients given the high volume of business.

But Kahler disagreed.

"I don't think it's the appropriate decision to have total, free unrestricted access to the office."

Stanaway then asked what the likelihood was of people being killed in this situation by a lone gunman.

Kahler said it was very low for any Work and Income office in New Zealand.

To Worksafe prosecutor Dale La Hood, Kahler said bulletproof glass could have a deterrent effect.

The hearing is expected to take a week.