FACS data is stored as FCS files and remain in the computer as long as they are not deleted. If they have been deleted there is a smelling rat. So they SHOULD be retrevible by the first author by files name, data of acquisition, time etc which should all be recorded in the student’s notebook. Nobody CAN alter FCS files anytime unless it is deleted. That being said, flow experts can analyse somebody’s else’s FCS files for them when they describe the paramters that they analysed. For e.g. FL1 for annexin and FL3 for PI or FL1 for CD4 and FL3 for CD8. But there are a lot of visible signs if FCS data is manipulated and can be easily found out by experts in the field. For eg the BD Annexin ppt that is posted as a model shows double negative cells constant for all conditions which is done on one voltage setting. If the double negative moves down then some X or Y parameter has been altered for sure. Auto fluorescence, uncompensated data, altered data, manipulated data etc. by flow can be very easily detected by voltage settings and by analysing data.