CSI: Fatal Conspiracy

During the Third Case - Tapped Out you will eventually get into the Room belonging to John Barrett, There are a few pieces of Evidence to be found in the Room, but for this achievement all you must do is pick up the lingerie from the Bed, once you have collected it bring up your PDA and go into Evidence then select the lingerie.

You can now freely rotate the underwear once the evidence collect icon appears click it then use the Swab from the collection tools, this will collect the first DNA sample do it once more to collect the second Sample.

Return to the Lab.
Go into the right hand lab room and use the DNA/Chemical Analysis machine then choose the DNA option select the Female DNA sample, click search - 4 possible matches will come up choose the 4th one.
Next do the exact same with the Male DNA Sample and again 4 Choices Will appear once again choose the 4th one.

Once both samples have been Identified the Achievement will pop.

These are the video walkthroughs for case 3 but also show you how to get the Sunday, Sunday, Sunday! and a tough job achievements in these videos All credit goes to setw18. I did not make these video`s.