But in an unusual reversal of roles in the High Court yesterday, the prosecution pressed for a man's 'guilty' plea to be quashed, and the defence asked that the plea be upheld.

The case in question involved a stable helper who admitted in April to drugging a race horse, but fresh evidence has since surfaced to indicate that he admitted to a crime he did not commit.

The High Court heard that, a week after Ng Guan Hup, 65, pleaded guilty, a closed-circuit television recording showed that he had not even entered the stables in the Singapore Turf Club that July day last year.

And an analysis of the liquid in the vial found in his locker showed it did not contain any of the banned substance with which he is supposed to have injected the horse.

Arabian Star, the horse belonging to his nephew Charles Leck, had tested positive for a performance-suppression drug.

Ng also admitted to doping Mr Leck's two other horses, Kingtrap and Justohelp, but these are to be taken into consideration.

With the new evidence uncovered casting doubt on his admission, the prosecution thus informed the lower court further investigations were needed.

It then applied for a discharge not amounting to an acquittal for Ng, arguing that his continued conviction was unsafe and would result in serious injustice.

Ng, adamant about his guilt, objected to the application for the discharge through his lawyer.

District Judge Shaiffudin Saruwan rejected the prosecution's application in May. The prosecution then appealed against his decision.

Yesterday, Deputy Public Prosecutor Lau Wing Yum said that, given the uncle-nephew relationship between Ng and Mr Leck, the bizarre step Ng took to admit to the charge and his opposition to a discharge, it was highly possible that he had, in some way or another, abetted the offence in a conspiracy.

DPP Lau urged the court to quash the conviction pending further investigation to determine the real culprits. He said that investigations into whether Ng was involved in abetment of conspiracy were going on.

Ng, therefore, should be given a discharge not amounting to an acquittal so the prosecution can revive the charge later if further investigations show some culpability on his part.

But Ng's lawyer Harold Seet asked the court to dismiss the appeal and let the conviction stand.

He said there must be serious injustice or error on the part of the district judge before the High Court could intervene.

The prosecution's new evidence was a bare assertion, he added.

Justice Lee Seiu Kin said he needed to consider the matter and will give a written judgment.

Ng can be fined up to three months or fined or both for mischief.

elena@sph.com.sg