When they conducted their study with about ten people, they found out that the dogs found all the "victims" in multiple trials when none of them were under stress. It also showed that the "victims" with the long version of that gene were also found for most of the trials conducted unlike the short version "victims"; the short version of the gene was not found during the trials.
Sessa and his colleagues found that the victim's scent must have changed when under stress caused by this gene and it confused the dogs in the search. I agree with what Sessa and his team found in their study. It showed that the people with the short version of this gene made it harder, almost impossible for the dogs to find them when they are under stress. Although, a bigger study is needed to confirm their findings of whether being stressed out or scared changes their body scent, they seem to be on the right track with the serotonin transporter gene.