A construction worker found a blood-stained knife buried on OJ Simpson’s property “years ago” — and gave it to an off-duty cop who kept it in his home before finally turning it over to police, a report says. Law enforcement sources told TMZ that the blade is a folding buck knife, which is now being tested for hair and fingerprints after being handed over to the L.A.P.D.’s Robbery Homicide Division in January. It will be tested for DNA and other biological evidence at the department’s Serology Unit next week, sources told the site.