Better than an eyewitness; Cold cases: DNA identification can catch culprits, but police must collect evidence they ignored.


CRIMINALS have always left their calling cards at crime scenes; police could not always read them.

New technology has improved police department's reading skills so much that they are now solving old cases they had shelved. These breakthroughs require all police departments to rethink how they identify and collect evidence because blood spots the size of a pencil tip can yield the identity of a criminal.

Baltimore County police recently announced they had closed a 14-year-old murder thanks to this sophisticated DNA technology. In that case, an armed robber confronted a couple on the porch of their Woodlawn home. The robber raped the woman, and then fatally shot her husband.

As part of their collection of physical evidence, police recovered a tiny amount of the killer's sperm. At the time, the sample was too small to run any identity tests.

This past spring, homicide detectives forwarded the small sample of sperm to Cellmark Diagnostics, a Rockville firm known for its forensic work. They also forwarded a small sample of Leon Copeland's blood. Homicide detectives had long suspected that Copeland, who had a history of violent robberies, was involved in the crimes but had been unable to assemble enough evidence to charge him.

Using a technique known as polymerase chain reaction, scientists have been able to replicate tiny bits of DNA into amounts large enough to use in identifications. The lab matched the samples, and Copeland was charged with the 1986 murder.

DNA tests are becoming synonymous with exonerating wrongly convicted defendants, even rescuing a few from death row. These same tests can be equally effective in solving crimes so long as police are trained to read and analyze the evidence criminals leave behind.

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