Horatio is investigating the murder of a diamond dealer in a parking garage He meets Eugene ,a.mildly developmentally disabled man who washes people's car windows and witnessed the murder. Eugene is actually helpful. It turns out he calls the killer Colton because that was the logo on the backs of his sneakers. Later,he finds out Eugene has been savagely beaten and is fighting for his life in the hospital..He searches "Colton" 's home and discovers traces of Eugene's blood on a shirt. He goes to where the man is cutting a deal to throw his partner under the bus. Horatio confronts him and when the creep has the temerity to say he did Eugene a favor by killing him, tells him that Eugene just put him away for life. Then he intercepts a county transporter so he can pay for Eugene's burial. Great episode capped by the touching relationship between Horatio and Eugene.
Review of Witness to Murder
