Butcher street was a gold mine for the MPD, Chance included. When they had found themselves going through the building that Johnson was residing at, they found a load of Hellfire Arms in crates, along with a large load of cash. Millions of dollars were estimated to be in each of the crates.
Cash accumulated from 2 years of Dripper killings, maybe even more which were done under the MPD's nose.
The officers deduced that this large warehouse was where the cash was stored for Drip Work Inc. The crimson surface covering the walls and parts of the floor were ominous, mystic and weary at times.