Cellebrite expert Ian Whiffin walked jurors through one of the most contentious pieces of evidence in Karen Read’s case Monday.

Karen Read 's second murder trial is now underway. But this trial is not it for Read's legal troubles. Read, 45, is accused of killing her boyfriend, Braintree native and Boston police officer John O'Keefe outside a Canton home in January 2022. Read's first trial in O'Keefe's death ended in a mistrial in July.

Read’s first trial — which saw 74 witnesses take the stand and throngs of Read fanatics outside the courthouse over two months — ended in a hung jury in July.