Hey,
I found this old paper about shooter AI, it is not up to date but a lot of the concepts can be used 
http://d3d3lmnnzi1has5jb200.g00.extremetech.com/g00/TU9SRVBIRVVTMSRodHRwOi8vd3d3LmNnZi1haS5jb20vZG9jcy9zdHJhYXRtYW5fcmVtY29fa2lsbHpvbmVfYWkucGRm/$/$
Hope this helps
Elias