The body was found a good mile, maybe a bit more, N and some W of the Mansion, say a third-mile west of the main creek and up on the bluff where the Broad Branch Rd runs, not near any trails within the park itself...on the edge of the park in a thicket.
Still, with transport, even a bicycle, he could have done what you say.
BTW, I just saw somebody from the DC police saying where she was found was NOT near a jogging trail.