Mixture samples: In a DNA-sample with more than one contributor collected from a scene of a crime, e.g. a group rape, it is of interest to extract the individual DNA-profiles from the contributors. Standard STR-analysis typically returns 10-12 systems plus Amelogenin gender identification marker. A model for output from "Applied Biosystems Amplifier STR SGM PLUS" kit is established and estimated on the basis of a controlled laboratory experiment, performed by the Department of Forensic Medicine, University of Copenhagen.