A method of repairing DNA double-strand breaks for forensic DNA genotyping, comprising the steps of: (a) providing a forensic, non-supercoiled DNA sample comprising a target region containing a DNA double-strand break and a short tandem repeat; (b) providing at least a pair of single-stranded DNA targeting fragments, wherein the 3' end of each single-stranded DNA of a pair is proximal to the target region, with one single-stranded DNA targeting fragment encompassing at least 15 nucleotides of homology to one side of the target region and having its 3' end within 0-10 bp to one side of the STR and the other single-stranded DNA targeting fragment encompassing at least 15 nucleotides of homology to the opposite side of the target region and also having its 3' end within 0-10 bp to one side of the STR; (c) adding to the single-stranded DNA targeting fragments RecA protein or a functional RecA protein homologue able to search for complementarity between a targeting DNA fragment and the genomic DNA sequence with a double-strand break of interest as well as being able to perform the subsequent DNA binding and DNA invasion; (d) adding SSB or functional SSB homologue with the same function as SSB to the RecA protein or homologue and the single stranded DNA targeting fragments; (e) adding the DNA sample of step (a) and incubating until a strand invasion of the targeting fragments into the forensic DNA molecule has occurred; and (f) adding DNA polymerase and dNTPs, and incubating the resulting mixture until the invading strand has extended, wherein the strand comprises sequences from the targeting fragment and the forensic DNA molecule. (a) providing a forensic, non-supercoiled DNA sample comprising a target region containing a DNA double-strand break and a short tandem repeat; (b) providing at least a pair of single-stranded DNA targeting fragments, wherein the 3' end of each single-stranded DNA of a pair is proximal to the target region, with one single-stranded DNA targeting fragment encompassing at least 15 nucleotides of homology to one side of the target region and having its 3' end within 0-10 bp to one side of the STR and the other single-stranded DNA targeting fragment encompassing at least 15 nucleotides of homology to the opposite side of the target region and also having its 3' end within 0-10 bp to one side of the STR; (c) adding to the single-stranded DNA targeting fragments RecA protein or a functional RecA protein homologue able to search for complementarity between a targeting DNA fragment and the genomic DNA sequence with a double-strand break of interest as well as being able to perform the subsequent DNA binding and DNA invasion; (d) adding SSB or functional SSB homologue with the same function as SSB to the RecA protein or homologue and the single stranded DNA targeting fragments; (e) adding the DNA sample of step (a) and incubating until a strand invasion of the targeting fragments into the forensic DNA molecule has occurred; and (f) adding DNA polymerase and dNTPs, and incubating the resulting mixture until the invading strand has extended, wherein the strand comprises sequences from the targeting fragment and the forensic DNA molecule.