The suspect placed under arrest, 32-year-old Leonard Bajramaj of Stamford, is described as a former patient.
Bajramaj is accused of providing Rubins with narcotics and not calling emergency workers when he overdosed at his house.
Bajramaj phoned Stamford EMS shortly before 6:30 p.m. last night. An emergency staff arrived to find Rubins unconscious.
Police are waiting on a medical examiner's report to determine the exact time of death and what drugs were in Rubins' system.
At first authorities believed the death was an accidental overdose.
But after interviewing Bajramaj, he was charged with first-degree manslaughter Thursday morning. He was held on $500,000 bail.
His prior record includes charges of violating a protective order and disorderly conduct, and he uses multiple aliases.
Rubins was suspended from Greenwich Hospital for an addiction for painkillers.