(And by God I think our penchant for compartmentalization has gotten excessive now that we have to refer to people by numbers...)
I would be exceedingly interested in receiving a sample of tissue you obtained, hopefully you have preserved it in as pure an alcohol is locally availible and in a dark bottle to protect the specimen from light. I fear it may degrade substantially before reaching me.
Based on yours and other reports, I have a hypothesis that there may be symbiotic organism that is being bred or cultivated by our pale adversies. My colleagues scoff at this idea, but I am convinced, that we somehow lack a vital piece of information in understanding the movements of vampires. From our contact tracing studies, we are fairly certain that somehow there is more daylight movement of vampires than we previously assumed.
My hypothesis is that the symbioite, if it exists, like the black wings of certain moths has certain light trapping structures to absorb the light in an exceedingly thin and flexible layer and converts the sunlight into heat. While this would limit the time the symbioite could withstand the sunlight it would afford temporary protection for its host.
It could be that somehow there is a special fabric that is used for cloaks, but my own experiments show that the weaves of most fabrics are porous, or transparent enough to sunlight that (unless wrapped in multiple, cumbersome layers much like a mummy with movement severely restricted) that they would provide little protection. Our pale adversaries are much too graceful to be thus encumbered.
Another specimen, so degraded as to be virtually useless, was provided to me, and in that account it was mentioned, that the cloak moved strangely and rippling almost independently. In that case the vampire was slain and in the sunlight both the vampire and the majority of the cloak was rapidly consumed in the usual exothermic reaction. Perhaps the light trapping layer was breached and the underlying organism shares similar characteristics as a vampire and was consumed in a similar way.
Given that new vampires don't often appear in cloaks, and our observation that only very old vampires have some ability to walk in daylight, my thought is if the cloak is organic it must somehow increase in size and grow and the vampire ages. My assumption is that the vampire must somehow be cultivating and sustaining it. Hence, like other examples we see in nature as in certain slime moulds that feed off of leaf litter and the dead, my thoughts have turned to there being some type of symbiotic relationship that has developed. My thought is that the "cloak membrane creature" must somehow derive certain benefits from the vampire and vice versa the vampire obtains the benefit of mobility in sunlight.
The mere mention of "magic" no longer winds me up as it once did. My certainly in the natural order of things and the value of science is firm.
Washing hands, as normal.