A Canberra man charged over an explosion at the Australian Christian Lobby (ACL) headquarters last year has killed himself.

Jaden Duong, 36, was on bail awaiting trial in the ACT, accused of lighting gas cylinders inside a van parked outside the building in December.

Duong had pleaded not guilty to the charges of arson and property damage.

In an earlier court hearing his lawyer told the ACT Magistrates Court he does not deny his involvement, but will contest the charges on mental health grounds.

The blast caused about $10,000 worth of damage to the ACL's Deakin office.

Police documents tendered to the ACT Magistrates Court revealed Duong had hired the white van at Canberra Airport and purchased the gas bottles in the lead up to the explosion.

In an interview with police, Duong said on December 21, 2016, he "drove around for a while" before parking the van outside the ACL's headquarters.

Police: Why did you pick that location?

Duong: Because I dislike the Australian Christian Lobby.

Police: Are you affiliated with any group?

Duong: No.

The documents also showed he later apologised to police, saying "sorry about the mess".

After the explosion CCTV footage captured a man in dark clothing, believed to be Duong, walking along a nearby street with his arms outstretched in front of him.

According to the documents, Duong arrived at the Canberra Hospital about an hour and a half after the explosion, with burns and blisters on his face and arms.

The statement of facts revealed information recorded in Duong's treatment notes, including that he said he was "not a huge fan" of the ACL, or religion in general, due to their beliefs and position on sexuality.

But he said the decision to drive to the ACL was "spontaneous" as he was not able to find another suitable location.

Earlier this year AFP Commissioner Andrew Colvin told a senate estimates committee their investigation confirmed he was not targeting the ACL.

"We don't believe his motivation was to make any point on the Christian Lobby. His motivation was driven by mental illness and a desire to commit suicide," he said.

ACT Policing have confirmed officers attended a non-suspicious death at 4:30pm yesterday.