Police believe it was a robbery gone bad.
It's not clear if the suspects knew who the victim was before they robbed him.
Cromwell is charged with murder, robbery, criminal possession of a weapon and possession of stolen property.
Williams is charged with murder, robbery and criminal possession of a weapon.
The suspects will be arraigned Thursday in Staten Island Criminal Court in Stapleton.
Both suspects have criminal histories. Williams is on parole after serving almost three years for burglary.
Cromwell was previously arrested on an auto theft charge.
The robbery was caught on surveillance video and helped link the suspects to the crime.