A forensic scientist received an analysis request $($discipline not relevant$)$ and was asked to compare a set of unknown specimens with a set of reference samples. The expert was asked to evaluate if the unknown and references sets share a common origin. After conducting appropriate comparative examinations, the expert observed some concordances and also some dissimilarities between the compared features of the uknowns and references. The expert estimated that the probability of the specimens in the two sets matching was $0\mathrm{.}9.$ The expert also consulted a reference database of similar objects and estimated a random match probability of $0\mathrm{.}0001.$ What are the most appropriate propositions to be used at the first level of the hierarchy of propositions?