  We present 3-D models of dust distribution around beta Pictoris that produce
the best fits to the Hubble Space Telescope Advanced Camera for Surveys'
(HST/ACS) images obtained by Golimowski and co-workers. We allow for the
presence of either one or two separate axisymmetric dust disks. The density
models are analytical, radial two-power-laws joined smoothly at a cross-over
radius with density exponentially decreasing away from the mid-plane of the
disks. Two-disk models match the data best, yielding a reduced chi^2 of ~1.2.
Our two-disk model reproduces many of the asymmetries reported in the
literature and suggests that it is the secondary (tilted) disk which is largely
responsible for them. Our model suggests that the secondary disk is not
constrained to the inner regions of the system (extending out to at least 250
AU) and that it has a slightly larger total area of dust than the primary, as a
result of slower fall-off of density with radius and height. This surprising
result raises many questions about the origin and dynamics of such a pair of
disks. The disks overlap, but can coexist owing to their low optical depths and
therefore long mean collision times. We find that the two disks have dust
replenishment times on the order of 10^4 yr at ~100 AU, hinting at the presence
of planetesimals that are responsible for the production of 2nd generation
dust. A plausible conjecture, which needs to be confirmed by physical modeling
of the collisional dynamics of bodies in the disks, is that the two observed
disks are derived from underlying planetesimal disks; such disks would be
anchored by the gravitational influence of planets located at less than 70 AU
from beta Pic that are themselves in slightly inclined orbits.
