Lyric discussion by fnordatpanix 

Cover art for Murder lyrics by David Gilmour

My impression is that these lyrics referred to Roger Waters. I somehow get that the "ending another man's life" was a nod to Roger's treatment of Richard Wright who was effectively kicked out of the band during the Wall sessions. Roger also had a menacing stare and the "in the background, the eyes that just stared" could be reference to that as well.

Song Meaning