WHO DAT

DNA profiling was originally developed as a scientific method for determining paternity. Use of DNA in capturing and putting away criminals is relatively new. The first case in which it was used was in 1986, and it actually exonerated a suspect, then lead to the capture of the real perpetrator. The very next year, DNA was used to put away a rapist, the first prosecution of its kind in the United States. 

Since that time, the validity of the science has been challenged less and less, till it became accepted as reliable science. However, DNA evidence is still occasionally thrown out of court on the basis of the process with which it is collected.