What is the best way to identify KRI?

Well this a quite nice question. First of all you need to identify context, in another words you need to identify the risk. Next you should identfy the contributers in materializing the risk. Ask the question what are the things that wi help in making this risk possible? Have the list check each item they should be (specific, measurable and sensitive). Keep the items holding these characteristics and drop any item does not holding anyone of them. Then use your risk appetite to set your signals. Once you are done you would have a relevant KRI thats support an early signal to you risk. Take an example of a risk like hitting an object while reversing a car. Distance between the car and object is what we want to measure. The car reverse sensor peeps will indecate the how close we are to an object thus we stop before we hit it. I hope this can cover your answer.

By proper mapping and tagging of indents that have been reported..

To go through the process and try to identify the vulnerable objectives of specific department/ process. All such vulnerable objectives will derive KRIs which will be monitored on monthly basis for monitoring.