Hernandez's defence has gone after how it was tested, and how it was matched with Hernandez's DNA.
Hernandez lawyer James Sultan on Friday got a state police crime lab scientist to acknowledge that a shell casing that had Hernandez DNA on it could have been contaminated by chewed blue bubble gum that was stuck to it before it was found by police. She said the gum was never tested.
She also testified that Hernandez's DNA matched DNA on rolling paper found near the body of Odin Lloyd in June 2013. Lloyd was dating the sister of Hernandez's fiancee.
She is expected to resume her testimony Monday.