Former senator Mark Arbib has put the blame for Labor’s botched home insulation program squarely on the shoulders of his ex-colleague Peter Garrett.

Mr Arbib claimed the former environment minister was the man in charge of the program, which has been linked to four deaths, when giving evidence at a royal commission into the scheme on Monday.

Before the hearing even began, Mr Arbib caused a stir by slipping into the Brisbane Magistrates Court complex through a back door and avoiding the waiting media scrum.

Peter Garrett. Photo: AAP

The commission later said the former Labor powerbroker had been allowed to make the unusual entrance after he raised “security concerns”.

In the witness box Mr Arbib laid the blame for the home insulation debacle on Mr Garrett, who will get his chance to respond on Tuesday.

He said while he’d co-ordinated the government’s stimulus programs as parliamentary secretary to the prime minister, Mr Garrett was the one designing the program.

“I didn’t have any decision-making role in terms of the HIP (home insulation program), I was working with the co-ordinator-general’s office,” he said, adding that Mr Garrett was the minister responsible.

Mr Arbib said he didn’t know that three tradesmen had died under a similar scheme in New Zealand in 2007.

He claimed he never saw an email sent to the government in July 2009, which raised the risk of electrocution and the NZ deaths.

“I would have been ringing alarm bells,” he said.

Mr Arbib said the prospect of deaths or serious injuries was never raised as a safety risk.

“Death was never mentioned as a prospect,” he said.

Parents of Matthew Fuller, Christine and Kevin Fuller.

But death became a reality under the program when Queenslander Matthew Fuller, 25, was electrocuted while driving a metal staple into an electrical cable while installing foil insulation on October 14, 2009.

It was the same practice that led to the deaths of the three NZ installers.

Mr Arbib said he never thought about suspending or reviewing the program after Mr Fuller’s death.

“I don’t recall considering that,” he said.

He said he wasn’t involved in any high-level discussions about Mr Fuller’s death either.

“I was informed that the prime minister’s office and Mr Garrett were dealing with it,” he told the inquiry.

“I wasn’t being asked into those meetings.”

The royal commission is investigating what advice Labor received about the scheme and whether the four deaths could have been avoided.

Mr Arbib is due to finish giving evidence on Tuesday, while the man he claims was responsible for the scheme, Mr Garrett, is expected to enter the witness box immediately afterwards.

Former prime minister Kevin Rudd is due to appear on Wednesday.

AAP