"THE Crown does not have to prove why Eric Forrest did what he did," a jury has been told by the prosecution about an alleged shotgun murder on a property outside Mudgee.

"It just must prove beyond reasonable doubt that he did commit murder."

In closing submissions in a Supreme Court trial in Sydney , the jury members were asked to consider words spoken in intercepted phone calls, the topography of the alleged shooting site and whether they could rely on evidence heard at the trial from people who admitted to being ice users around the time of the alleged crime.

While the prosecution focused on what was described as the "honest and frank" evidence of a farm worker who says he saw Forrest murder David Collisson, the defence asked the jury to approach that evidence with "great caution".

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