A man's body was discovered in a property in Molesworth Road in Plymouth in the early hours of Tuesday morning.
A local man and woman, aged 50 and 29 respectively, were arrested on suspicion of murder.
Three people have appeared before magistrates in Plymouth charged with two separate murders in the city.
The body of 33 year-old Keith Dance was found in a house in Stoke on Monday. 29-year-old Jacqueline Cooke and 50-year-old Ian Gollop have been jointly charged with his murder.
In a another case, Ian Neville was charged with the murder of Richard Brown at the Complex pub in Keyham Road in Plymouth on Tuesday. All three will make a first appearance before Truro Crown Court on Monday.
Police have confirmed that a man found dead earlier today was 33 years old and lived in Molesworth Road in Plymouth. Officers say they can't name him until formal identification has been carried out. His family have been told about his death.
A forensic post mortem is taking place later which is hoped will identify the actual cause of death.
A 50 year old man and a 29 year old woman remain in police custody. Both were arrested earlier today on suspicion of murder.
"I want to reassure the local community that the two suspects and victim were all known to each other. I can also share with you that all three had recently come to the attention of police for an earlier incident.
"There are a number of specific lines of enquiry that the investigation team is following. This includes carrying out house to house enquiries and looking into the relationship history of the deceased and the two suspects. In addition there is some complex forensic retrieval and analysis being carried out.”