Is it illegal to get DNA off a restaurant fork or from their garbage left on the curb?
Interesting questions. Wonder if any of the lawyers here have any thoughts about them.
Even if for the sake of argument you would collect DNA in that fashion from three individuals and then submit it to a laboratory for DNA analysis, in what context might you use the information, how credible might the information be to those who may have the authority to act on it, and what repercussions, if any, might the DNA results cause? All of this is only speculation at this time, and it sounds more like a plot of a good science fiction novel rather than a practical plan with a reasonable chance of success.