How has crime investigations changed since John Wayne Gacy?

As of June 22, 2013 human remains found by

hikers on Mount Olympus in 2010 were positively identified as

Daniel Raymond Noe. The 21-year-old Illinois native, who was

reported missing in 1978, was originally thought to be a victim of

Gacy. Gacy was sentenced to death for 12 of these killings on March

13, 1980 and since that time, crime investigations has changed

making the investigations more faster and better. A crime is based

on a legal definition prescribed by a governmental entity, such as

a state legislature or the US Congress and now DNA could tell us

the color of eye and hair of a subject something that in Gacy's

time wasnt possible.