Here are some quick and dirty brainstorm sketches, in the order of their inception:
From the outset the audio clip inspired in me a modern-day noir aesthetic, much like Scorsese's The Departed. I tend to be very raw and stream-of-consciousness in my initial impressions.
The antagonist became a blend of influences, ranging from Anthony Quinn, Jack Nicholson, Christopher Plummer, and other film heavies with imposing voices and physical presence.
Initially Beckett was a more upright, prissy hoodlum. I thought it made for interesting contrast and it seemed to fit the slightly nasally voice. I blocked in an entire thumbnail pass of this character, but was unsatisfied with the performance and tone, and scrapped it...
In the end, Beckett became more cool, intense, and hunched over - an arrogant James Dean / Matt Damon type.