Methods for establishing the genotype of a DNA sample, and methods for investigating the potential sources of a DNA sample arising from a plurality of source, are provided, the methods being based on a method including: analysing the sample to produce a data profile for the sample for a locus; proposing a suggested genotype; generating a first stage profile for the locus for the suggested genotype; adjusting the first stage profile to account for one or more factors to give a simulation profile; and comparing the data profile and the simulation profile to provide an indication of the likelihood of the data profile given the suggested genotype. The methods in effect make adjustments to take the first stage profile, potentially through one or more intervening profiles, to the simulation profile, the simulation profile being an anticipation of the data profile which would be expected to occur for that suggested genotype in practice. The methods potentially include adjustments for one or more of preferential amplification and/or stutter and/or allele drop out and/or allele drop in and/or stochastic components and/or noise and/or preferential degradation and/or the relative contributions from the sources.