You have the story wrong. There is no searchable database of DNA. There are only blood samples from newborns.
The police wanted access to the sample of a single suspect. The straightforward thing to do would of course have been to get a sample directly from the suspect. But as the case was so high profile and there had just been a public debacle with another arrested and eventually released suspect, the police preferred to risk the integrity of the scientific research project rather than do their job the normal way.
It's infuriating because it was so unnecessary. But police prestige was on the line and here we are.
The police wanted access to the sample of a single suspect. The straightforward thing to do would of course have been to get a sample directly from the suspect. But as the case was so high profile and there had just been a public debacle with another arrested and eventually released suspect, the police preferred to risk the integrity of the scientific research project rather than do their job the normal way.
It's infuriating because it was so unnecessary. But police prestige was on the line and here we are.
Edit: source (Swedish) https://sv.m.wikipedia.org/wiki/Mordet_p%C3%A5_Anna_Lindh