On Wednesday, the final witness, a government forensic scientist, maintained that he does not believe the curvature on the base of a metal ornament was caused by Robert Kissel - who was found dead in 2003 - striking it with a baseball bat, despite the defense suggestion that his methods were flawed and that he was ``anxious'' to provide evidence for the prosecution.

Kissel, 41, is accused of drugging her husband with a sedative-laced milkshake before bludgeoning him to death with a heavy metal ornament on November 2, 2003. She accepts she inflicted five fatal blows to his head but says she cannot remember how she did it. Kissel has testified that her husband came at her swinging a baseball bat and that she used the metal ornament to protect herself. She denies the murder charge and is out on bail.

Earlier in the trial, the defense had suggested that the curvature on the base of the metal ornament had been caused by the impact of Robert Kissel's baseball bat.

Wednesday, Dr Wong Koon-hung agreed with defense counsel his conclusion that there was no significant impact between the baseball bat and the metal ornament was based upon the logic derived from his experiments, and that if his tests had been flawed ``in any significant way'' then so would be his conclusion.

Wong had used two new Mizuno baseball bats to strike sheets of lead in a ``controlled experiment'' to simulate the scenario of a furious Robert Kissel striking the metal ornament.

Wednesday, defense counsel Alexander King SC asked Wong, when he used the brown baseball bat to strike the lead sheets, ``how many of those left paint residue?''

Wong replied, ``none of them,'' adding that neither was there paint residue left when he used the other black painted baseball bat.

Tuesday, Wong had said he would also expect to find ``wood grain pattern'' left by the bat on the metal base of the ornament, because when he conducted his simulated tests, his newly purchased wooden bats had left such patterns on the lead sheets.

``Did you conduct any tests to see what types of wood, each of the bats was made of?'' asked King. ``No,'' replied Wong. Wong said he was mainly interested in the appearance and weight of the bats.

``You would agree would you not, different woods like different metals, have different hardness?'' asked King.

Wong agreed, but said that he was pretty sure that both his experimental lead sheets and the metal base of the ornament were ``99 percent lead.'' King noted that the lead sheets were ``noticeably thinner'' than the base of the ornament and ``that would affect the indentation that would arise'' when struck with force.

He also suggested that since Wong's original statement was subjected to alteration by his superiors, he must have been ``anxious'' to provide the right results for the prosecution.

In re-examination, Wong maintained he found ``conclusive'' results to show the metal ornament was not struck with force by a wooden baseball bat.

The prosecution will submit its final speech on Friday before justice Michael Lunn.

albert.wong@singtaonewscorp.com