Found (heuren). Second aorist active indicative of heuriskō.
That he had been in the tomb four days already (auton tessaras ēdē hēmeras echonta). Literally, “him (accusative object of heuren) having already four days in the tomb.” See Joh 5:5 for the same idiom (etē echōn) for expression of time (having 38 years). In Jewish custom burial took place on the day of death (Act 6:6, Act 6:10).