A man named an accused in an extortion case allegedly involving former Mumbai police commissioner Param Bir Singh and others was arrested on Thursday afternoon, a police official said.

The crime branch of Mumbai Police, which is probing the extortion case registered at suburban Goregaon police station, arrested the accused, Vinay Singh, from a cafe, the official said. This was the fourth arrest in the case, in which Param Bir Singh, dismissed assistant police inspector Sachin Waze and one Riyaz Bhati are among the accused.