On the basis of the photo's of the victims Jane says it is the same woman who knitted the scarf and rose. First of all the rose looks like it has been crocheted instead of knitted and secondly you cannot identify the maker of a knitted item (this precisely).
Dr Montague is not a Decision Scientists, she is a Data Scientists.
Decision Science uses probabilities to determine the best decision to achieve a desired result (usually in a business environment). Data Science looks for meaningful correlations in data sets, basically they do what Dr Montague described her program doing, they look for patterns and connections in compiled data.
The only use a doctor of Decision Science would have in a murder investigation would be to help the killer choose their next victim.
As suggested by the name, Decision Science is concerned with decision making, it has no investigatory application.