Advanced scientific techniques have not improved the rate at which murder cases and manslaughter crimes are solved. Approximately 65% of these crimes were cleared in 2012, compared to 90% in the 1960s, according to Federal Bureau of Investigation (FBI) data. Although DNA and other forensic techniques make it easier to examine evidence, it is thought that the solving rate decreased because of changes in the nature of violent crimes. Premeditated gang and drug-related crimes, which generally have less witness cooperation, became more prevalent. However, murders and manslaughter crimes in the 1960s were more likely to be impulsive crimes of passion where the victims had close relationships with their perpetrators.
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