He was played by the late Leonard Nimoy.
Doctor Mayfield was a brilliant heart surgeon, he had been working with Doctor Edmund Hiedeman on developing anti-rejection drugs for organ transplants. While Doctor Hiedeman had been working his whole life on the process, Doctor Mayfield had joined much more recently but was still taking half the credit, and was urging him to release there findings before anyone else released there's so they could claim the glory and money. But Doctor Hiedeman refused, until the tests were done to a conclusive degree.
Following intercepting a telegram for Doctor Hiedeman from a colleague in Germany urging them to do at least another year of tests, Doctor Mayfield planned to get rid of Hiedeman so he could release early and steal the glory. As Doctor Hiedeman needed a valve operation, Doctor Mayfield being the leading heart surgeon was going to do it. To allow himself to murder Doctor Hiedeman without anyone getting suspicious, he dyed some dissoluble suture (surgical thread used for operations) to the color of permanent suture so that it would break down over the period of several days, causing Hiedeman to die but making it look like simply another heart problem that occurred during his recovery.
During the operation, he slips his dissoluble suture into Hiedeman, and constantly criticizes Hiedeman's long standing Nurse, Nurse Sharon Martin (who is rightfully convinced Mayfield is evil) for watching him to closely rather than doing her job. Afterwards it seeming he did nothing wrong, Sharon apologizes to Doctor Mayfield, but then finds some of the suture on the floor while cleaning up, Mayfield meanwhile spys her doing this with a mirror. Confronting him about it, she knows it doesn't feel right and accuses him of doing something to Doctor Hiedeman. Mayfield coldly dismisses her claims and tells her if she has evidence of foul play to take it to the police, but for now to do her job and appears to leave, but instead stays behind and listens in, as Sharon books an appointment with the supplier to see if its the right suture or not the next day.
However as she is leaving, Mayfield confronts her outside her car and bludgeons her to death with a tire iron. He then takes her keys, being careful not to leave any fingerprints and then goes through her bag, to make it look like someone had wildly foraged through there, as part of his plan to frame someone else for the crime. The next day he waits outside Sharons apartment, and waits till her roommate, fellow Nurse Marcia Dalton leaves, before using the keys to break in. Then he ransacks the place making it look like someone was searching for something, and then hides a few bottles of Morphine he stole under her sink. Making it look like Sharon was involved in stealing and selling drugs from the hospital and got killed by an addict looking for more.
Then going to office, he calls for Sharon on the phone, when told she is dead he feigns shock, but carries on adjusting his clock. However at this point Columbo comes in to question Doctor Mayfield, he takes notice of what Mayfield was doing, before asking him about Sharon's personal life, Mayfield denies knowing anything and says he must go to check on Doctor Hiedeman. Staying polite, Columbo already has his suspicions and slyly compliments Mayfield on his concentration, at managing to do a mundane task while upset, Mayfield tries to cover it up claiming he always does it and its a reflex.
Mayfield then goes to see Doctor Heideman, finding he's alright the two chat, Heideman asks if his condition will change soon, and knowing he will die soon Mayfield tells him it will. Later Mayfield hosts a party at his home, Columbo comes to visit intending to question Mayfield. Mayfield finds him and Columbo fills him in on the discovery of the Morphine in Sharon's apartment, everything seeming to go to plan, Mayfield informs him that Sharon did have access to the drugs cabinet. However, Columbo reveals something he found strange, the fact there were no fingerprints at the seen of either crimes, as a desperate drug addict wouldn't be so careful.
Realizing Columbo isn't buying the set up, Mayfield organizes a meeting with Marcia, and while on the walk down the beech, manipulates her into remembering a Veteran that Sharon had worked with at the drugs clinic and later dated several months earlier called Harry Alexander. He then convinces her, he must be the one who linked to the Mophine and most likely the killer, convincing her to tell Columbo as soon as she can, to throw him off the trail. Sure enough Marcia does tell Columbo when he asks her about Sharon's personal life, but suspicious at such a direct answer to a general question, Columbo gets her to reveal it was Doctor Mayfield who gave it to her, heightening his suspicions about him.
Columbo goes to visit Hiedeman at the hospital, and finds out that Sharon distrusts Mayfield, as well as her being sad on the day of Hiedeman's operation (which Hiedeman assumes was just cause they were close), Mayfield finds them, and angrily kicks Columbo out, arguing that Doctor Hiedeman is to weak for questioning. Outside Columbo asks Mayfield about Harry, but he claims to barely know the man.
A day later, Mayfield catches Columbo talking the cleaning lady, trying to find out about Mac (something Shannon wrote on a note pad, Mac being an acronym for there supplier of equipment). Mayfield asks if they have arrested Harry, but Columbo tells him after looking him over he's convinced he's clean and innocent. And he also believes that Sharon wasn't involved in drugs, and they were planted to throw the police and him off the right track. He then notes that only he and doctor Hiedeman had access to the drug cabinet apart from Shanon. Mayfield angrily denies the accusation, but Columbo insists he didn't mean anything, but then reveals he found out from the cleaning lady Sharon was still upset after Hiedeman's successful operation and wonders allowed why she would if he was going to be okay?
To make it look like Columbo is wrong, Mayfield breaks into Harry's apartment, and when he arrives drugs him. While unconscious, Mayfield injects an overdose of Mophine into his arm, and leaves the empty bottles and the needle to make it look like Harry really was the addict and accidentally killed himself. However Harry wakes up after Mayfield leaves, still drugged he stumbles unable to see and hear clearly, out of his apartment and falls down the stairs, the fall breaks his neck and kills him.
The next day Columbo goes to visit Mayfield and tells him about what they discovered. Mayfield assumes the case is closed, but Columbo reveals one detail that doesn't make sense, Harry was left-handed, so why was the injection wound in his left arm? And thus reveals that he believes Harry was murdered to set him up. Mayfield tries to put the blame on Marcia, but Columbo doesn't buy it. However he laughs of his accusations claiming he would have no motive to do all these things.
Mayfield later finds Columbo talking to Heideman again, angry he threatens to have the hospital launch an official complaint. But in this time Columbo has found out what MAC means, and about the suture, realizing what's really going on he goes with Mayfield to his office to confront him. Mayfield dismisses the idea of swapping permanent suture with dissolving suture on the grounds that dissolving suture is a different color and it would be noticed during surgery. Columbo however correctly guesses that it could easily be dyed the right color.
Mayfield laughs this off, and accuses Columbo of just making up theories. Finally having enough of him, Columbo angrily slams a care fare down on Mayfields desk, and dropping all pretenses reveals he believes he is the murderer, and warns him that if Doctor Hiedeman dies in the next few days, he will force them to have complete autopsy, revealing the true cause of his death. He then leaves, warning Mayfield to look after Hiedeman.
Realizing the danger he is in, Mayfield is forced to slip some poison into Hiedeman's medicine, making it look like his body is rejecting the valve transplant and thus forcing them to replace it with another one, and forcing him to save the life of the man who he started all this to kill. Following a successful operation however, Columbo and several policemen burst in with authority to search everything, to try and find the dissolving suture that Mayfield took out of Hiedeman.
Seemingly angered by this Mayfield temporarily grabs Columbo, but then agree's. Columbo's men find nothing and it looks like Columbo was wrong, sadly he leaves Mayfield's office. Mayfield assumes he's achieved victory, but at that moment Columbo bursts back in and reveals he knows the truth. Realizing it was completely out of character for such a cold and control man to loose control like that, he realizes it was a ploy for Mayfield to sneak the suture into Columbo's pocket this making it look like he was innocent. Columbo then reaches into his pocket and finds his theory to be true and thus Mayfield is taken away for murder.
- Doctor Mayfield holds the honor of being the only Villain in the shows run who caused Columbo to completely loose his temper, while Columbo did occasionally get angry when he found himself dealing with criminals who held a complete disregard for human life. Doctor Mayfield's sheer sociopathy caused him to near lose it.