Five suspects have been charged in connection with the ketamine-induced death of Friends actor Matthew Perry.
The doctor and the actor's assistant have entered plea agreements to federal charges.
Two others, a doctor and a woman known as the "Ketamine Queen," were arrested Thursday, ABC News reported.
Police have carried out a major investigation following Perry's death.
The uncovered underground crime network appeared to be distributing large quantities of ketamine to Perry and others.
The US Justice Department said the main defendants in the case are Jasvin Sangha and Dr. Salvador Plasencia.
Police believe the five defendants took advantage of Perry's drug addiction to enrich themselves.
US Attorney Martin Estrada said the defendants knew they were putting the actor in danger, but they did it anyway.
Plascencia allegedly received ketamine, and other participants in the scheme supplied the drug to Perry.
Over the course of several months, the actor received about 20 liters of ketamine in exchange for $55,000.
