Counsel for alleged NCA bomber Domenic Perre ask for trial’s end be delayed, attack credibility and mental health of key witnesses

Auditory hallucinations and crimes under a different name – the NCA bombing case’s key witnesses are under attack, and the marathon trial may be extended.

The motivations and mental health of the NCA bombing trial’s two key witnesses have come under fire – and that could see the case extended even further past its original time frame.

Prosecutors were due to conclude their Supreme Court case against alleged murderer Domenic Perre on Thursday, after seven months of evidence.

On Wednesday, however, defence counsel said that should not occur due to newly obtained information about two witnesses considered “linchpins” in the prosecution case.

Barrister Gilbert Aitken said he had obtained a psychological “opinion” about a former prison inmate who claims Mr Perre had “brought him into the family”.

That opinion follows accusations, made in court, the witness experienced auditory hallucinations of a female voice after serving prison time with Mr Perre in the 1990s.

Domenic Perre, left, a diagram of the bomb, bottom right, and Detective Sergeant Geoffrey Bowen and his wife Jane, top right.

Mr Aitken said the reliability of self-styled gunsmith Allan “Gadget” Chamberlain was also in question due crimes he committed, in 2013, under a different name.

“We will be saying that Mr Chamberlain got a benefit, in that he received a suspended term of imprisonment for converting semiautomatic weapons to fully automatic,” he said.

“The fact he got that benefit, we say, motivated him to respond to a subpoena and volunteer to come here and give evidence in this case.”

Mr Perre, 64, has pleaded not guilty to murdering Detective Sergeant Bowen, and attempting to murder NCA lawyer Peter Wallis, with a parcel bomb in March 1994.

In his evidence, the former inmate – whose identity is suppressed – said Mr Perre drew a diagram of the bomb for him during their time in the Adelaide Remand Centre.

He further claimed to have witnessed the 1996 racially-driven murders of Ron Noga and Adrian Slusarczyk from his cell window around that same time.

Mr Perre looks toward the former NCA office from the roof of a multi-level carpark during the court's tour of key scenes in the trial. Picture: NCA NewsWire / Brenton Edwards.

The man refuted Mr Aitken’s suggestion he had told “a pack of lies” about the bombing to the court, and about his name and medical credentials to lovers and friends.

In his evidence, Mr Chamberlain said Mr Perre had wanted to go into business with him turning semiautomatic guns into more lethal, fully-automatic weapons.

He also claimed a cache of guns, ammunition and books found under his stables belonged to Mr Perre, and that he was only storing them.

However, he also conceded he felt “psychologically” threatened by police when interviewed about the bombing.

On Wednesday, Mr Aitken said prosecutors should not be permitted to close their case until the new information had been assessed and a timetable considered.

“These are matters that may require, potentially, recalling witnesses,” he said.

The trial, before Justice Kevin Nicholson, continues.