Police arrested 20-year-old Chanel Lewis and charged him with second-degree murder.
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"Karina in this case actually supplied the DNA for us," Case supervisor Katey Nori said.
Police said that evidence taken from the victim was found under her fingernails, on her neck and from her cellphone at the scene.
"We were able to recover DNA in three places, and one being on her actual body," Nori said.
Nori, along with Chief of Laboratories Tim Kuperschmid and DNA Analyst Rachael McCloskey, discussed some of the case elements Monday.
"If requested we will do that DNA testing on that evidence and see in the end what role it plays," McCloskey said.
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McCloskey and a team of five others looked for biological evidence, touch DNA or skin cells where a suspect may have touched the victim.
"It's not uncommon to have the DNA developed from the evidence without knowing who that DNA was left by," McCloskey said.
Police said early on in the case that the DNA didn't match anyone in the national database.
After following a lead that police said led them to question Lewis, investigators revealed they were able to get a DNA sample from him.
"When an individual gives a sample and it's taken by a member of the NYPD, it's called a consensual sample," Nori said. "So when that sample comes here it would be that of a known individual and if it does match, it would be a direct match."
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The lab team said advancements in technology are making DNA testing even better.
"As the new technologies come on board, we are applying it to these cases and we are gaining more and more information from evidence we may not have been able to solve in years past," Kupferschmid said.
The case was ongoing over a six-month period, and analysts continued to make many comparisons.
"When you do this much testing and there were so many investigative leads during the time period, it was very gratifying at the end to see that there would be a match," Nori said.
Click here for more coverage of Karina Vetrano's murder.