The present invention provides a method for detecting or enriching for a target deoxyribonucleic acid (DNA) present in a nucleic acid sample, said method comprising: (a) fragmenting a nucleic acid sample to generate nucleic acid fragments including a target fragment containing said target DNA and non-specifically ligating an adaptor sequence to an end of said fragments; (b) rendering said fragments at least partially single-stranded; (c) contacting the at least partially single-stranded fragments of step (b) with oligonucleotides A and B of a single target-specific nucleic acid probe; (d) ligating oligonucleotide B of said probe to the part of the single-stranded portion of said target fragment which is hybridised to oligonucleotide A of said probe to produce a probe-target fragment hybrid; and (e) detecting or enriching for said probe-target fragment hybrid.