Rebecca had no cuts on her hands. She did have some abrasions, and some dried blood on the right hand was noted in the autopsy report.
Its very unlikely that the abrasions described would have deposited enough blood to account for what was found on the handle of the knife.
Also, its unknown when those abrasions occurred. They may have occurred post-mortem.
Details from the autopsy report below:
On the posterior aspect of the radial right hand, there are four red abrasions ranging from punctate to 1/16 inch in diameter. On the medial aspect of the right third finger (the surface between the third and fourth finger), over the distal portion of the middle phalanx, there is a 1/2 x 5/16 inch abrasion with skin tags on the palmar edge.
On the posterior aspect of the middle phalanx of the left 3rd finger there is a horizontally oriented, 1/8 inch, linear abrasion.
There is a small amount of dried blood on the posterior right 3rd finger and on the posterolateral aspect of the mid-right 4th finger and distal right 4th finger.