Judge Paul Lacava told Stephanie Beattie, who had also worked at the Cranbourne police station, she had stupidly breached a trust for her own interests in a way that "struck at the heart of the criminal justice system".

He said in the County Court that Beattie, 23, had ruined her career through a lack of judgement and maturity.

Beattie last year allowed her lawyer to tender four written references to a magistrate when she pleaded guilty to two relatively minor driving offences.

She had written the references herself - including one from a colleague in the police force - and forged the signatures.

The police ethical standards department started an investigation after the colleague's reference was queried by a prosecutor because it had been written against police policy.

Last Thursday, Judge Lacava told Beattie, who had pleaded guilty, it was a tragedy her career had been short-lived. "The police force cannot have members in its ranks that fabricate evidence put before a court".

Beattie received a six-month sentence wholly suspended for 12 months.