An assay method for calculation of source contribution and detection of the presence or absence of copy number variations (CNVs) in one or more genomic regions within a mixed sample, the assay comprising the steps of: interrogating selected loci in the mixed sample by: introducing a first set of fixed sequence oligonucleotides to a mixed sample under conditions that allow the fixed sequence oligonucleotides to specifically hybridize to complementary regions on one or more loci in or associated with a genomic region; introducing a second set of fixed sequence oligonucleotides to the mixed sample under conditions that allow the fixed sequence oligonucleotides to specifically hybridize to complementary regions on at least one polymorphic locus; introducing one or more bridging oligonucleotides under conditions that allow the bridging oligonucleotides to specifically hybridize to complementary regions in the loci, wherein the one or more bridging oligonucleotides are complementary to a region of the loci between the regions complementary to the fixed sequence oligonucleotides of each set; ligating the hybridized oligonucleotides to create contiguous ligation products complementary to the loci; amplifying the contiguous ligation products to create amplification products; and analysing the individual amplification products through sequence determination or hybridization techniques; wherein one or more selected loci are interrogated for copy number and one or more selected loci are interrogated for polymorphisms of interest in nucleic acids corresponding to a major source or a minor source in the mixed sample; calculating source contribution by determining loci content from amplification products derived from fixed sequence oligonucleotides that identify one or more selected loci interrogated for polymorphisms of interest in nucleic acids corresponding to a major source or a minor source in the mixed sample; and detecting CNVs by determining loci frequency from amplification products derived from fixed sequence oligonucleotides that identify one or more selected loci interrogated for copy number. interrogating selected loci in the mixed sample by: introducing a first set of fixed sequence oligonucleotides to a mixed sample under conditions that allow the fixed sequence oligonucleotides to specifically hybridize to complementary regions on one or more loci in or associated with a genomic region; introducing a second set of fixed sequence oligonucleotides to the mixed sample under conditions that allow the fixed sequence oligonucleotides to specifically hybridize to complementary regions on at least one polymorphic locus; introducing one or more bridging oligonucleotides under conditions that allow the bridging oligonucleotides to specifically hybridize to complementary regions in the loci, wherein the one or more bridging oligonucleotides are complementary to a region of the loci between the regions complementary to the fixed sequence oligonucleotides of each set; ligating the hybridized oligonucleotides to create contiguous ligation products complementary to the loci; amplifying the contiguous ligation products to create amplification products; and analysing the individual amplification products through sequence determination or hybridization techniques; introducing a first set of fixed sequence oligonucleotides to a mixed sample under conditions that allow the fixed sequence oligonucleotides to specifically hybridize to complementary regions on one or more loci in or associated with a genomic region; introducing a second set of fixed sequence oligonucleotides to the mixed sample under conditions that allow the fixed sequence oligonucleotides to specifically hybridize to complementary regions on at least one polymorphic locus; introducing one or more bridging oligonucleotides under conditions that allow the bridging oligonucleotides to specifically hybridize to complementary regions in the loci, wherein the one or more bridging oligonucleotides are complementary to a region of the loci between the regions complementary to the fixed sequence oligonucleotides of each set; ligating the hybridized oligonucleotides to create contiguous ligation products complementary to the loci; amplifying the contiguous ligation products to create amplification products; and analysing the individual amplification products through sequence determination or hybridization techniques; wherein one or more selected loci are interrogated for copy number and one or more selected loci are interrogated for polymorphisms of interest in nucleic acids corresponding to a major source or a minor source in the mixed sample; calculating source contribution by determining loci content from amplification products derived from fixed sequence oligonucleotides that identify one or more selected loci interrogated for polymorphisms of interest in nucleic acids corresponding to a major source or a minor source in the mixed sample; and detecting CNVs by determining loci frequency from amplification products derived from fixed sequence oligonucleotides that identify one or more selected loci interrogated for copy number.