Who else did Richard Harrow kill in Season 3, Episode 1?

He's pretty likely an unlucky driver/minion of Manny's.

I don't think we have enough information to be sure, but based on:

1. The victims location (sitting outside Manny's house waiting in a car), and


2. The context (Manny's response to hearing a honk indicates that he was expecting to be picked up),

I think it's safe to assume that Richard's mission to avenge the murder of Tommy's parents by killing Manny also claimed the life of a hapless wheelman or accomplice for Manny's planned trip that night.