Fair question. In order to find a stalker you have to think like a stalker.
For the record, I am not a stalker, LOL, but if I were, here's what I think:
The report says he was gunned down en route to the company's AGM. Companies typically make public their annual general meetings and post info like this on their websites, newsletters and social media accounts. Enough Google searches on the company and its CEO would almost certainly tell you where and when this meeting was going on and that he would be there.
Once the where and when are established, it's just a matter of getting to the city (if the shooter is not already a resident or living within a 100-mile radius of NYC). The meeting's venue would also certainly be published. Once you know where the venue is, search for nearby hotels. Arrive a day or two early. Start scoping nearby hotels and restaurants looking for the mark. Follow him around.
Really, it probably would not be too hard if you were seriously angry and wishing to settle a vendetta.
EDIT: I was correct, here's a link to info on their AGM:
https://www.unitedhealthgroup.com/n...uhg-business-outlook-investor-conference.html