Who said anything about saving lives?
The aim would be to catch criminals. That could be murderers, but it could also be rapists, muggers, burglars, thieves, conmen, etc etc
Lots of people in this thread.
Being as you are arguing for this database maybe you could answers some questions please.
You need to know how effective at improving conviction rates this database would be?
Do you have any figures?
How many crimes have there been where there is a lack of suspect and the database would help? i.e What % of cases would this extended database help find a suspect?
I would expect that a very high % of cases there is already a suspect without the database, in these case the extension of the database is not needed as once you have a suspect you can take a sample and eliminate or not.
Given the potential gain in convicted criminals and the cost of the database what would be the cost per-conviction? Is this the most efficient way to spend the money?
We can catch many more criminals if we reduce the requirements for warrants and allow much greater general surveillance. If catching more criminals is your aim why not do this too?
Do you trust the police not to abuse any new power?