Marty Rudoy, an attorney who represented Rebecca’s family during the initial stages of the investigation said this:
“The dirt on the balcony is not consistent with the actual dirt on her feet. It was dirt from a garden.”
Screen captures of photos shown along with Mr. Rudoy’s statement in support of his claim. The balcony looks pretty clean, IMO.
Photos courtesy of Marcia Clark Investigates the First 48 - The Spreckels Mansion Mystery
Thanks to Mr Rudoy for saying that, it's what many here believed all along. I just wish he'd said so years ago, it would have saved us a few arguments here! I don't recall from my one visit to the area what the soil looks like in this area, but it looks more like the kind of dark colored landscaping mulch or topsoil/potting mixture that landscaping companies put in flower beds and around bushes.