>What do you think the odds are that the birefringent
>material was from the varnished paint-brush handle? Do you
>think the end of the paintbrush (that is missing) was used
>to assault JB? Or, do you think a bit of the varnish got on
>the perp's finger and that it was a digital assault?

With the combination of birefringement material and the celulose, I tend to think the paintbrush handle was used.

>FWIW, I'd go with digital assault. I think the killer broke
>the paintbrush into three parts, throwing one piece back
>into the paint tote, using one for the construction of the
>garrote, and the third bit was stuffed in his pocket or
>misplaced amongst all the junk in the basement or rolled
>under something and not discovered.

I wouldn't be surprised if the missing portion of the paintbrush handle was still in the house but overlooked by LE. Although, you'd think it would have been discovered by now if that were the case. If the paintbrush handle was used, it seems there would evidence of it on the portion left at the crime scene. I haven't seen any information released on this.

>Does anyone know what the 3 lengths of paintbrush were?

I'm not sure what you're asking. Are you wondering why it was broken into three pieces?