It started with blood type and fingerprints. How forensic tools have evolved since the 1970s

Forensic science in criminal investigations began with the identification of blood types found on the crime scene.

The science wasn't enough to crack the case, yet it did guide investigators in the right direction — and excluded potential suspects with differing blood types.

By the 1980s, it was becoming clear to law enforcement that forensic science was evolving. The specifics of those advancements, though, weren't clear.

Some law enforcement held on to potential evidence, while others did not. The weight of those decades-old decisions are now coming to light, with DNA advancements, forensic genealogy and nationwide databases.

For cold cases that retained evidence, there's a world of hope that decades-old mysteries can be solved.

Forensic evidence in the 70s relied heavily on the pre