A chief medical examiner testified Friday that a homeless illegal immigrant may have already been internally bleeding before allegedly being punched by a former Mount Kisco police officer.Dr. Charles Wetly says Rene Perez could have been bleeding for up to 24 hours before he was allegedly hit in the gut by former police officer George Bubaris. The prosecutors still believe Bubaris delivered the fatal blow that led to Perez?s death. Bubaris is charged with manslaughter. A surveillance video from an hour before Perez?s death shows him inside a Mount Kisco Laundromat removing a sweatshirt and walking around. The doctor says Perez would still be able to eat, walk and pull off the sweatshirt even if he was bleeding internally.The prosecution is trying to prove that the injury happened between the time Perez left the Laundromat and when he was found on Byram Lake Road 40 minutes later.The jury is expected to see the case sometime next week.