Police have warned of potentially "explosive" consequences unless they can keep DNA samples of people who have been questioned but not charged.
The police powers in England and Wales have been challenged
They said there could be a public "furore" if a high-profile sex offender could have been caught earlier had police been able to keep samples.
The warning came from the Association of Chief Police Officers in Scotland (Acpos) to the justice committee.
The DNA of people arrested and released is retained in England and Wales.
At present, DNA samples taken when people have been arrested in Scotland are destroyed if the person is not charged or convicted.
The Holyrood committee will scrutinise the Public Order and Criminal Justice Bill on Tuesday.
Labour MSP Paul Martin has tabled an amendment to the bill which would enable the police to retain the samples.
In a written submission to the committee, Acpos secretary William Rae supported the move.
"Individuals who would commit crimes of a sexual nature rarely come into police custody and opportunities to record their fingerprints and DNA are limited," he said.
"Given recent high profile cases on the investigation of sexual offences, this could present a potentially explosive reaction were it realised that a serial sex offender could have been identified at an earlier stage of an investigation, had the evidential samples been retained from previous contact with police on unrelated matters.
"The fact that such samples would have been retained were the offences to have occurred in England and Wales would undoubtedly add to the considerable furore which would likely occur."
Mr Rae said the "ineffectiveness" of existing legislation was shown by a case in Easter Ross.
He said that swabs taken at the scene of two housebreakings matched records held by North Yorkshire Police.
"The individual from whom this sample had been taken had subsequently been acquitted and the DNA record retained in error," he said.
"Consequently, there being no other evidence to link the suspect with the crimes, the investigation could not be progressed."
The law in England and Wales has been challenged on human rights grounds.
However, Mr Rae said the House of Lords had upheld the practice on several grounds, one of which was that the public gain was "vastly more important than the marginal individual loss of rights".