Police say a technique enabling them to search their DNA database for relatives of offenders will be used sparingly.
Police national forensic services manager John Walker said the technique resulted this week in the conviction of a Christchurch man on two sexual assaults committed many years ago.
Mr Walker said police have established protocols determining how familial matching can be used and will be used only in serious cases such as rape or homicide.
He said familial matching is relatively new in New Zealand and police have resolved legal and privacy questions associated with the technique.
