HONOLULU (KHON2) — Experts say DNA testing is how most cold cases are now being solved. Get Hawaii's latest morning news delivered to your inbox, sign up for News 2 You It helped identify a suspect in the murder of a McKinley High School student with evidence preserved from the 70s. Dawn MomoharaSketch of suspect Sketch of suspect's vehicle DNA testing has been part of criminal investigation procedures since the 1980s, according to forensic experts. "It's very powerful because the match can be determined in the absence of eyewitnesses or other corroborating evidence," stated David Haymer, Professor of Molecular Biology at the University of Hawaii. "But, it's also very powerful for excluding individuals as potential contributors to having been involved in a crime scene as well. Schweitzer brothers sue Hawaii County agencies for malicious prosecution, conspiracy Kinship or genealogy testing is commonly used for decades-old cold cases like the murder of Dawn Momohara, the 16-year-old McKinley High School student was allegedly sexually assaulted and strangled by her classmate, Gideon Castro, in 1977. Castro was arrested Tuesday, nearly 50 years after the attack, following a DNA match obtained from his son. "You expect a partial match because people that are biologically related share some of their DNA. So, parents and children, for example, you expect will share about half of their DNA or 50% of their DNA in common. Then when you have you have aunts, uncles, nieces, nephews, expect them to share about 25%," said Professor Haymer. DNA evidence can last indefinitely if preserved correctly, per Haymer. In Momohara's case, DNA found on her shorts was used to profile the suspect. "They'll go ahead and extract the DNA, and then a series of genetic markers are produced that give you the so-called DNA profile. You can compare that profile to individuals that are considered suspects," stated Professor Haymer. Haymer added the methodology has improved considerably over the years, providing more definitive results. Download the free KHON2 app for iOS or Android to stay informed on the latest news "It's pretty amazing how quickly this technology has become critical to solving cold cases and effective," said Professor Haymer.