Commander Peter Peters is a non-canonical character created for ITV's 2009 adaptation of the novel Why Didn't They Ask Evans? He is a family friend of the Savage family and a frequent guest of Sylvia Savage at Castle Savage. Commander Peters is portrayed by Warren Clarke.
In this adaptation, it is Peters and not Dr Nicholson who makes points out the discrepancies in Frankie Derwent's account of how her car accident at the gate of Castle Savage took place. Later he "takes charge" of the investigations into the death of Claude Evans. A self-assured person, he concludes that Tom Savage must have murdered Evans because he kept a pet snake and Evans had died from snake venom. Peters moves quickly to arrest Tom and brushes aside and silences Bobby Attfield when he wishes to point out some contrary evidence. Part way through the process of arrest, Peters realises himself what Bobby had wanted to say, that extracting snake venom required specialised skills and equipment that went beyond merely having a snake as a pet. He then arrives at the conclusion Bobby had come to, that it is probably Nicholson who is responsible. He hurriedly moves to arrest Nicholson and is happy to take the credit for coming to this conclusion himself.
Peters tells Miss Marple that he has served 40 years in the Flying Squad. This suggests that his rank of Commander is that of a Commander in the Metropolitan Police instead of a Commander in the Navy. A commander is a senior rank unique to the Metropolitan Police introduced in 1946 which is just above Chief Superintendent and just below Deputy Assistant Commissioner.