A permanent or temporary marker is embedded within a hydrogel plug used in a biopsy procedure to indicate the location of a suspicious lesion so that the marker may be found in a subsequent surgical procedure. A combination of at least one permanent and at least one temporary marker may be used. Inserts of differing sizes and shapes may also be placed into the hydrogel plugs during their manufacturing process and removed from the plugs after the plugs have cured so that air-filled cavities are left in the plug. These cavities are temporary but may be used to augment location of a permanent marker.