Detective 'did his best' on shooting case

The lead investigator into the death of a man at a crayfish farm has told an inquest he put in his best effort given limitations at the time.

The Coroners Court of Queensland this week reopened an inquest into the death of Jeffrey Lawrence Brooks, who was shot through the chest on March 13, 1996, at Beenleigh on Brisbane's southern outskirts.

The 24-year-old, who had recently graduated with a degree in marine biology, was found in a utility vehicle's cabin and lying on top of a shotgun.

On Thursday, the lead detective from the case, Michael James Condon, faced questions as to whether his investigation was "adequate and complete".

Mr Condon, who ranked detective sergeant at the time and retired this year as a Queensland Police assistant commissioner, acknowledged in hindsight some parts of the investigation were "messy" but he brought the case to its conclusion.

The Brook's' family's solicitor, Michael Turner, cross-examined Mr Condon and asked about potential shortfalls, including not interviewing a second person who claimed to hear a gunshot on the day in question.

Mr Turner said Mr Brooks' father Lawrence had to push Mr Condon to obtain phone records that narrowed the time of death, and there were failures to test the body for firearms residue or question the alibis of some farm workers.

"You have highlighted some issues and what your opinion is I should have done. I did what I thought was best at the time and I stand by that," Mr Condon said.

"Are we smarter and wiser now? Absolutely, but at the time I thought it was the right way to go and I did what I could with the information I had."

Mr Condon said he had kept an open mind during the investigation and found the the "most likely" cause of Mr Brooks' death was an accidental shooting involving an unsafe firearm.

Mr Turner asked Mr Condon if he lowered the priority of investigating Mr Brooks' death because he thought it was an accident while he had a lot of murder cases to handle.

"They take higher priority sometimes depending on the type of murder. For instance, (one case at the time) involved the murder of a person by 18 Finks motorcycle gang members," Mr Condon said.

"Sad as it is, in the public interest, I had to commit resources to that and there were numerous investigations like that. Did I give it 100 per cent every day after that point? No, I didn't. Did I do my best to balance it? Absolutely."

Mr Condon admitted to counsel assisting Sarah Lane that he had "tension" with Lawrence Brooks, who has accused Mr Brooks' fellow workers of killing his son out of fear he was planning to close the farm or expose their crayfish theft.

"I was frustrated by the continued position that Mr Brooks was taking, that he wasn't being open-minded. Could I have handed myself better at the time as a detective sergeant? Probably," Mr Condon said.

"I don't believe I threatened (Lawrence) Brooks. I have no doubt at the time I was short with him."

Mr Condon also said he conducted his own tests with the shotgun that killed Mr Brooks in order to see whether it was possible to snag the trigger while dragging it through the farm utility vehicle's cabin.

The inquest continues.