A HIGH COURT judge has slammed a police investigator for not making clear to an alleged victim on what rape means under the law.

Justice Kan Ting Chiu said the cop had defined rape wrongly and stressed that officers should have 'proper understanding of the offences' being probed.

The judge made the remarks when explaining why he convicted police officer Lawrence Lim on three charges of kicking, slapping and pushing his 23-year-old Indonesian maid in 2006.

He had admitted to hitting the maid with his fist and knuckles on two earlier occasions.

But Lim, defended by lawyer Lee Teck Leng, initially faced 13 charges in all, including one for rape and six other sexual offences for which he was acquitted.

In the course of the 28-day trial that ended in July, the judge had, among other things, found many discrepancies and inconsistencies in the maid's account of the sexual offences.

Justice Kan in his written grounds released on Wednesday said this came as ' no surprise, ' leading to Lim's acquittal on the more serious sexual offences.

The judge noted serious sexual offences were probed by the Serious Sexual Crimes Branch of the Criminal Investigation Department.

' It is important that SSCB officers have proper understanding of the offences they investigate.'

He said if the officer had proper knowledge of the offence, she would not have told the victim ' there is no rape without force or threat,' and would instead have advised the victim that rape is sexual intercourse without consent.

Justice Kan added that while sexual assault victims may not want to or are unable to describe the assault accurately,such descriptions are necessary.

Lim, 35, a staff sergeant of the Criminal Investigation Department, is appealing and is currently out on $70,000 bail.

He faces a jail term of up to 18 months and/or a fine of $1,500 on each of the charges and is awaiting sentence.