Posted on March 13, 2019 by Katie Mortimer and

The importance of proper investigation technique – A Council’s investigation process challenged in the LEC

A recent decision of the Land and Environment Court examined the way in which a Council investigating officer interviewed witnesses, and how the conduct of that officer ultimately affected the evidence relied on by the prosecutor. The decision provides useful guidance on the correct approach to interviewing witnesses and the importance of proper investigation techniques.

Ku-ring-gai Council (Council) commenced class 5 proceedings in September 2016 against John David Chia (Defendant) alleging the Defendant had committed an offence against the Environmental Planning and Assessment Act 1979, due to the unlawful cutting down and removal of 74 trees that were protected by the Council’s Tree Preservation Order.

The Defendant plead not guilty, and a lengthy hearing occurred where a significant number of issues were raised (resulting in 14 interlocutory judgments). In particular, the Defendant objected to the Council’s evidence, and the Council’s investigation of the matter.

Council Investigation 

During Council’s investigation, an investigator retained by the Council conducted various interviews with witnesses. During some interviews, he allowed witnesses to be interviewed together. One interview with a contractor occurred in the presence of another contractor, who on occasions intervened and assisted the interviewee answering questions.

On another occasion the investigator told a witness that he needed to speak with another contractor, as he may able to corroborate what had been said.

The Defendant raised issues with the investigator’s process, and submitted he broke rules about proper investigation technique. In doing so he contaminated the evidence that these witnesses gave, and deliberately created opportunities for witnesses to collude, or encouraged them to corroborate their versions of events.

The Defendant submitted that the Court should not accept the evidence, as it was a product of collusion between the witnesses and had been contaminated at an early stage of the investigation by the actions of the Council investigator.

Proper Investigation Techniques and Approaches 

In cross-examination the Council investigator agreed with a number of propositions put by Senior Counsel for the Defendant about proper interviewing practice.

These propositions, extracted from the case, are:

  1. It is important to keep an open mind during investigations
  2. It is important to keep witnesses separate
  3. Witnesses should never be interviewed together because there is a chance of contamination (of recollections) and the witness with the stronger personality may overbear the witness with the weaker personality
  4. Witnesses should be put in separate rooms so they cannot talk to each other to ensure that they give their [own] version of events and not an amalgamated version
  5. It is important not to suggest material to witnesses as to do so may influence what they say and deprive the investigator of the ability to check what the witnesses actually know
  6. By imparting information to a witness, he or she is put on notice in relation to specific issues which may mean that a complete and independent version of what occurred cannot be obtained
  7. Where it is within his control, the Investigator would not allow Witness A to come into contact with Witness B unless he had [taken] an independent version of facts from each of them (prior to the contact)
  8. If the Investigator ever became aware during an interview that multiple witnesses were present, he would separate them straight away.

(see paragraph [152] of the judgment)

These propositions highlight the inherent risks in interviewing a number of witnesses who have their own individual observations and recollections of an incident.

The risks of contaminating a witnesses’ recollection are well known. Care should be taken to ensure that a witness statement is only a product of the witnesses’ recollection and not someone else’s.

When investigation officers speak to multiple witnesses about incidents, those conversations should take place independently of other witnesses so that each witnesses’ recollection can be separately recorded, and unaffected by the recollection of any other person

The Court’s Findings on the Investigation 

During the cross-examination referred to above, the Council investigator accepted that the better practice was to have separated the witnesses when interviewing them.

After considering the evidence, the Court ultimately accepted evidence that the Defendant asked the Court to reject. However, Robson J took into account the investigative process adopted by Council’s investigator, and considered that when determining the overall reliability and credibility of the evidence. The Court did state that a number of the investigator’s practices were not preferable or desirable, and were less then ideal.

It is of vital significance that Council investigation officers adopt proper practices, to ensure that any evidence they collect is admissible in subsequent prosecutions. This case is a reminder of the importance of proper investigation techniques.

Read the Court’s judgment here Ku-ring-gai Council v John David Chia (No 15) [2019] NSWLEC 1, and our previous blog on an interlocutory decision in the proceedings here.

If you require advice on investigations or prosecutions generally, or to discuss this blog, please contact Carlo Zoppo, Partner on 8235 9705.