Denise Richards rehab car Charlie Sheen

X17 spotted Denise Richards visiting Charlie Sheen's Mulholland Drive estate today from about 3:30 - 5:30 pm PT.

Richards was visibly upset as she had a phone conversation over her car speakers while driving home. News of Sheen's recent breakdown must be hard to take for the actor's ex-wife with whom he has two daughters -- Sam, 5; and Lola, 4.

Though Sheen's rep has told X17 and other media outlets that his client is "in a rehab facility," it seems possible he may be seeking in-home treatment as he did in January after his Christmas Day blow-out with estranged wife Brooke Mueller in Aspen.

Richards could have been retrieving some of her daughters' belongings, perhaps knowing Charlie would be away for a while ... Or could she have been visiting Charlie?

It would make sense for Sheen, whose hit show Two and a Half Men is currently on hiatus because of the star's troubles, to do a more intense therapy at home so he could return to work more quickly. It may also appear less serious and just more of a "re-focusing" if he doesn't check in to a traditional rehabilitation facility but seeks some quick help at home and hires a sober coach.

Could in-home rehab be a PR move?