Wife did hire Richie, so easy to see
At the VERY beginning it was a dead give away.
Before John even gotten INTO his house, Richie, drove by (to see what the deal was), even John looks back at the car racing by.
The cue was his wife leaving the house to go for a walk or to the park, plus, the most obvious, HE KNOW JOHNS NAME AND SLIPPED UP by saying it, when going to shoot him, the girl was there, so he didnt do it.
On the way to the "hospital" Richie, I think, was thinking twice about killing him, so they went to the bar, who knows, maybe Richie really needed a drink to decide what to do.
Pretty simple story.