Surface-related multiples or internal multiples can produce artifacts in migrated images using one-way wave-equation methods. Salt-body-related internal-multiple removal remains a challenging problem for this approach. To investigate the effects of salt-body-related internal multiples on subsalt imaging, the boundary-element method is implemented in a one-way/one-return scheme to separate the primary transmission/reflection arrivals at the salt boundaries from the internal multiples. Numerical results demonstrate that the proposed method is effective for modeling primary transmission/reflection arrivals through/from irregular interfaces between strong-velocity-contrast media. Internal multiples are obtained through straight subtraction of primary reflection arrivals from full reflected-wave data. The image from prestack depth migration of these pure internal multiples using one-way propagators is compatible with some strong artifacts in the subsalt region from migration of full-wave data using the same one-way propagators. Results suggest that a significant part of artifacts in the subsalt region in the prestack image for the 2D SEG-EAGE salt model using one-way propagators might be caused by salt internal multiples.