Locating closest points

I have a point on line let say x,y and a list of points i want to find out the points closest to the point x,y at both ends for example




------------------------------ x1,y1
p1------------------------------|----------------------------------p2

and a list of point(p2,p3,p4,p5.......) now i want to find the closest two points


------------------------- p5-----x1,y1----p6
p1-----------------------|-------|---------|----------------------------------p2


is there any functioality available in arcobject that can perform this operation?