Diagnosis: Murder season 4

A friend of Steve's winds up dead in a friendly-fire incident involving a veteran cop, but the shooting may have been planned all along. Kim Johnston Ulrich played the conniving widow. Guest Star: Jonathan Banks.

Note: Michael Tucci does not appear in this episode.

Sloan and Jesse make contact with a patient who died from a genetically altered strain of smallpox. Steve and Amanda only have hours to find the cure before it's too late.

Note: Michael Tucci does not appear in this episode.

After faking an attack on herself just to win endorsements, a skater kills her accomplice and frames her rival.

Guest Star: Julie Benz

A string of murders occurs with the same killer signature. One of the victims supposedly called Mark, but it is after she was known to be dead. The case becomes personal when the killer starts calling Mark. Mark gets involved in the string of murders when the killer starts calling Mark. It gets more personal when the killer attacks Amanda. She manages to escape. Mark and Steve get closer to finding the killer. After the killer claims he didn't kill one of the victims, Mark and Steve look for the copycat murderer.

Guest Stars: Kurt Fuller, and John Schneider.

Sloan and Steve investigate a fashion show when they suspect a modeling agent of being a serial killer who murdered a private eye that discovered her secret, and her next target is one of Jesse's college buddies.

Guest Stars: Lesley-Anne Down and Jessica Collins

A cardiologist (Alan Rachins) and two business partners concoct a devious insurance scam to murder a man and pass him off as one of them, but when the partner who was supposed to be dead gets cold feet, he is murdered for real. Meanwhile, Mark adopts a basset hound belonging to one of Jesse's deceased relatives, as the others try to find a home for it.

Guest Stars: Alan Rachins, Josh Taylor, and Stephen Lee.

An ambitious female cop goes undercover tracking a terrorist (Eric McCormack) who blew up a delivery truck and killed the driver, injuring Mark in the process. The terrorist then orders a hit on Mark.

Note: Michael Tucci does not appear in this episode.

A bus crashes after T-boning a drunk driver. All of the passengers survive the accident, but one of them, an insurance adjuster and a rapist, is murdered in the aftermath, which is discovered by Mark when he is brought in to the hospital. The only suspects are the other passengers on the bus; a homeless ex-soldier with hallucinations of Vietnam, a college student who was the victim's next rape target, the widower of a cancer patient who fell into debt due to the victim scamming him into buying a phony policy, and a woman who is a master of insurance fraud. As Mark tries to make sense of what happened, the soldier is murdered as well, and now Mark is down to three suspects, none of whom seem to have been able to commit either murder. But a reexamination of the crime scene and an autopsy of the soldier reveals an unexpected culprit.
In a subplot, the accident and murder cause Mark and Steve to miss a Lakers game, and the coach arrives to give them free tickets to the next game - as a token of appreciation for their service. However, Dr Amanda, believing they're fakes, tears them up because the coach is a friend of the fraud-loving woman.

Guest Stars: Kathy Evison, Richard Riehle

The drug-addicted daughter of a senator is killed during an argument, but a senior aide tries to make it look like an overdose. However when the autopsy reveals inconsistencies, Mark discovers just how far the aide will go to protect the Senator's career.

Guest Star: Michael Cole, and John Rubinstein.

Sloan helps a district attorney (Piper Laurie) probe a drive-by shooting at a high school which left a popular teacher dead. But her stubborn insistence that a Korean teen is responsible makes finding the real killer a challenge.

Note: Michael Tucci does not appear in this episode.

This is a ‘DM’ Christmas episode. Even though there are plenty of Christmas trees on display, the storyline, initially at least, seems rather sad and grim, and it takes a little while for the Christmas associated themes to emerge. After many years, Mark's daughter, Carol Hilton (Dick Van Dyke’s real-life daughter, Stacy Van Dyke) comes home for Christmas in an attempt to escape the wrath of her abusive trucker husband, Bruce. She plans to file for divorce and move out of state for a new job. But, before she can put her plan into action, Bruce is found murdered. Unbeknownst to Carol, Bruce's actual job was illegally dumping toxic waste and blackmail, and she's likely the next target of his crooked associates.
The first standout element in this story is the imperfect, but very believable, relationship between Carol and Steve, her brother. Steve has always been overly protective of Carol, and he detested Bruce. One gets the impression that Carol may even have married Bruce in an impulsive attempt to escape Steve’s rather suffocating over-protection. When Steve is seriously injured and brought into Community General as a patient, a very moving bedside rapprochement takes place between brother and sister. The themes of love and forgiveness here make perfect sense in the context of a Christmas episode.
But the epilog of this episode is the real joy. Stacy Van Dyke delivers a brilliant rendition of ‘Have yourself a merry little Christmas’ while the regular cast goof around and decorate the Christmas tree in Dr Mark’s beach house. At the end, the regular cast, plus Stacy, all break the fourth wall and look straight into the camera to wish the audience, at home, a very ‘Merry Christmas’.

Guest Stars: Stacy Van Dyke (plays Carol Sloan Hilton), Anne Lockhart, John Capodice and Wanda De Jesus.

The head pediatric nurse turns out to be an ex-prostitute whose former madam is murdered after declaring her intentions to publish a tell-all book. The suspect nurse is defended by the lawyer and murderer Darren Worthy (David Dukes), who is trying to exploit the case for his own personal gain.

Sloan looks for clues to solve the decades-old murder of his mentor (Nicholas Pryor), when his body is found during hospital renovations, but another murder in the present disrupts his attempts.

Guest Stars: Tricia O'Neil, Nicholas Pryor, and David Purdham.

Sloan enlists his friend Ben Matlock (Andy Griffith) to defend Jesse, who's accused of murdering a resident. Guest Star: Lee Chamberlin.

Note: Michael Tucci does not appear in this episode.

With Jesse falsely accused of murdering Eric Spindler, Ben Matlock (Andy Griffith) gathers all the evidence to find the real killer. Guest Star: H. Richard Greene. Note: This was Andy Griffith's final appearance as Ben Matlock.

Note: Michael Tucci does not appear in this episode.

Dr Sloan assists veteran Private Investigator Joe Mannix (Mike Connors) with an unsolved murder case from 1973.
Note: This episode serves as a sequel to the Mannix episode "Little Girl Lost".
Guest Stars: Richard Gant, Julie Adams, Pernell Roberts, and Beverly Garland.

Note: Michael Tucci does not appear in this episode.

The prime suspects in the murder of a country star are a driven TV producer and her timid songwriter daughter.
Guest Stars: Deanne Bray, Barbara Mandrell, Billy Ray Cyrus, Terri Clark, Linda Davis, Billy Dean, Joe Diffie, Eddie Rabbitt, and Reba McEntire.

Note: Michael Tucci does not appear in this episode.

Psychiatrist Gavin Reed (Dwight Schultz) kills his estranged wife Claire (Teri Austin) and tries to frame a patient. But Mark and Amanda suspect otherwise and they soon learn Reed has sinister motives with his patients.
Guest Stars: Dwight Schultz.

Note: Michael Tucci does not appear in this episode.

A sexy, but sinister, pharmaceutical rep has every intention of winning Sloan's heart.

A beach boy is suspected of killing his girlfriend's brother – a gang member.
Guest Stars: Carey Van Dyke, and Shane Van Dyke.

Note: Michael Tucci does not appear in this episode.

A surgeon drops dead while operating on another doctor.

Guest Stars: Jack Klugman (plays Dr. Jeff Everden), Chad Everett, Wayne Rogers, Bernie Kopell

The pilot of an airliner escorting Sloan and Amanda to a medical conference in Europe, is killed.

A wealthy woman, Claire Whitfield (Brynn Thayer) and her lover cook up an elaborate plot to bump off her husband, Elliott (Wayne Tippit) and frame Mark. Brynn Thayer plays Leanne Macintyre on Matlock.^{[citation needed]}

Note: Charlie Schlatter and Michael Tucci do not appear in this episode.

A washed up comedian stumbles in his attempts to murder his more successful partner, whose ex-wife ends up dead in the pool. But evidence soon suggests he might not be responsible.
Guest Stars: Harvey Korman, Tim Conway (plays Tim Conrad), and Tom Gallop (plays Phil Zarkin).

Note: Michael Tucci does not appear in this episode.

A mad bomber whom Sloan helped put away breaks out of prison bent on revenge, but Mark discovers the bomber was not responsible for all attempts on his life.
Guest Stars: Carol Bruce, and Mary Kay Adams.

Note: This marks the final appearance of Michael Tucci as Norman Briggs.