There was! And there was partials for him on the body!
No there was/were not! One DNA sample on a pair of trousers completely unrelated to the murder and no partials "for him" anywhere. A number of mixed samples were found from which a number of males "could not be excluded."
DNA profiles in the UK are made up of 10 sets of two number "markers" - like this:
Marker 1 Marker 2 Marker 3 Marker 4 Marker 5 Marker 6 Marker 7 Marker 8 Marker 9 Marker 10
9:12 11:13 5:8 23:28 15:18 33:35 17:20 10:14 29:31 14:16
All of us have "markers" in common with other people - there were, from memory, something like 9 males known to the investigation with the same numbers at marker 9 -
none of them could be excluded from a sample in which the only available data was Marker 9 data (even SIO Dobbie himself!)
To complicate the matter even further, some of the partials had only one number recovered in a marker so, for example, a sample might recover number 11 at marker 2, and number 33 at marker 6 - now, not only can anyone with the same numbers as those shown here in these two markers "not be excluded" as a contributor, but anyone with one number the same, but the other different (e.g. 11:18 at Marker 2 and 33:39 at Marker 6) also can't be excluded.
One thing that
can exclude someone is if a partial sample is recovered, but both numbers at a particular marker are different from that person's profile, then it can safely be said that the sample did not originate from the person in question (so, for example, if a sample turns up the numbers 7:9 at marker 3, then the person from whom our hypothetical profile above originates
cannot be a contibutor to that sample, because his numbers at marker 3 are 5:8 )
There was a suggestion that the other semen samples on the t shirt could have originated from one male. Guess what the DNA reports said about that? If they did (originate from one person), then that male was
not Luke Mitchell, because there were markers in the samples that were not present in Luke's profile.