CARL RUSSO/Staff photo. Jordan Krahn, 10 and her brother Logan, 12 learn to extract DNA from strawberries by adding a solution to mashed strawberries. Former police officer and forensics expert Tim Craig taught the basics of forensics to children at the Kelley Library in Salem that included fingerprinting and handwriting analysis Tuesday afternoon. The 12 children who attended the class also learned about forensics through hands-on activities taught by Youth Services Librarian, Brittany Tuttle that included making a footprint casts and extracting DNA from strawberries. 7/22/2014.