As the missile nears its target, the Digital Scene Matching Area Correlation system takes over.

BBC: Tomahawk cruise missile

If the justices rule for King, more than 1 million DNA profiles that have been stored in a federal database for matching with future crime scene evidence may have to be purged and others will never be collected, leading some repeat offenders to go free, advocates say.

NPR: Court Takes Up Question Of Arrestee DNA Sampling

The database has been most useful in helping authorities find likely suspects by matching the DNA at the crime scene to the DNA results in the database, he said.

CNN: graphic